C++Talk.NET C++ language newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  Programming Puzzle Goto page 1, 2, 3 ... 17, 18, 19  Next          C++Talk.NET Forum Index -> C++ language (comp.lang.c++) View previous topic :: View next topic   Author Message Jatinder Guest Posted: Sat Jun 26, 2004 6:16 pm    Post subject: Programming Puzzle I found these questions on a web site and wish to share with all of u out there,Can SomeOne Solve these Porgramming puzzles. Programming Puzzles Some companies certainly ask for these things. Specially Microsoft. Here are my favorite puzzles. Don't send me emails asking for the solutions. Q1 Write a "Hello World" program in 'C' without using a semicolon. Q2 Write a C++ program without using any loop (if, for, while etc) to print numbers from 1 to 100 and 100 to 1; Q3 C/C++ : Exchange two numbers without using a temporary variable. Q4 C/C++ : Find if the given number is a power of 2. Q5 C/C++ : Multiply x by 7 without using multiplication (*) operator. Q6 C/C++ : Write a function in different ways that will return f(7) = 4 and f(4) = 7 Q7 Remove duplicates in array Q8 Finding if there is any loop inside linked list. Q9 Remove duplicates in an no key access database without using an array Q10 Write a program whose printed output is an exact copy of the source. Needless to say, merely echoing the actual source file is not allowed. Q11 From a 'pool' of numbers (four '1's, four '2's .... four '6's), each player selects a number and adds it to the total. Once a number is used, it must be removed from the pool. The winner is the person whose number makes the total equal 31 exactly. Q12 Swap two numbers without using a third variable. Given an array (group) of numbers write all the possible sub groups of this group. Q14 Convert (integer) number in binary without loops. Q3,12 are similar , Q7 is simple & I know there answer For the Rest please Help Wiating for reply. Back to top Joona I Palaste Guest Posted: Sat Jun 26, 2004 6:26 pm    Post subject: Re: Programming Puzzle Jatinder <jsfromynr (AT) sancharnet (DOT) in> scribbled the following on comp.lang.c: Quote: I found these questions on a web site and wish to share with all of u out there,Can SomeOne Solve these Porgramming puzzles. Programming Puzzles Some companies certainly ask for these things. Specially Microsoft. Here are my favorite puzzles. Don't send me emails asking for the solutions. Q1 Write a "Hello World" program in 'C' without using a semicolon. Q2 Write a C++ program without using any loop (if, for, while etc) to print numbers from 1 to 100 and 100 to 1; Q3 C/C++ : Exchange two numbers without using a temporary variable. Done to death here on comp.lang.c. Quote: Q4 C/C++ : Find if the given number is a power of 2. Easy with some bitwise arithmetic. Quote: Q5 C/C++ : Multiply x by 7 without using multiplication (*) operator. Easy peasy. Repeated addition will do the trick. Quote: Q6 C/C++ : Write a function in different ways that will return f(7) = 4 and f(4) = 7 int f(int x) { return x==4 ? 7 : x==7 ? 4 : 0; } Quote: Q7 Remove duplicates in array You can't remove anything from an array. You can only modify the values of its elements. Quote: Q8 Finding if there is any loop inside linked list. Should be covered in any basic data structures course. Quote: Q9 Remove duplicates in an no key access database without using an array Impossible without access into a no key access database. Quote: Q10 Write a program whose printed output is an exact copy of the source. Needless to say, merely echoing the actual source file is not allowed. Google for "quine". Quote: Q11 From a 'pool' of numbers (four '1's, four '2's .... four '6's), each player selects a number and adds it to the total. Once a number is used, it must be removed from the pool. The winner is the person whose number makes the total equal 31 exactly. This one is actually a full-blown game. Quote: Q12 Swap two numbers without using a third variable. And how is this any different from Q3? Quote: Given an array (group) of numbers write all the possible sub groups of this group. Search for the definition of a "power set". The algorithm shoudln't be too hard to figure out. Quote: Q14 Convert (integer) number in binary without loops. Already done here on comp.lang.c. -- /-- Joona Palaste (palaste (AT) cc (DOT) helsinki.fi) ------------- Finland -------- -- http://www.helsinki.fi/~palaste --------------------- rules! --------/ "This isn't right. This isn't even wrong." - Wolfgang Pauli Back to top Christian Bau Guest Posted: Sat Jun 26, 2004 6:38 pm    Post subject: Re: Programming Puzzle In article <22b2a6b6.0406261016.510e693b (AT) posting (DOT) google.com>, [email]jsfromynr (AT) sancharnet (DOT) in[/email] (Jatinder) wrote: Quote: I found these questions on a web site and wish to share with all of u out there,Can SomeOne Solve these Porgramming puzzles. Programming Puzzles Some companies certainly ask for these things. Specially Microsoft. Here are my favorite puzzles. Don't send me emails asking for the solutions. Q1 Write a "Hello World" program in 'C' without using a semicolon. Q2 Write a C++ program without using any loop (if, for, while etc) to print numbers from 1 to 100 and 100 to 1; Q3 C/C++ : Exchange two numbers without using a temporary variable. Q4 C/C++ : Find if the given number is a power of 2. Q5 C/C++ : Multiply x by 7 without using multiplication (*) operator. Q6 C/C++ : Write a function in different ways that will return f(7) = 4 and f(4) = 7 Q7 Remove duplicates in array Q8 Finding if there is any loop inside linked list. Q9 Remove duplicates in an no key access database without using an array Q10 Write a program whose printed output is an exact copy of the source. Needless to say, merely echoing the actual source file is not allowed. Q11 From a 'pool' of numbers (four '1's, four '2's .... four '6's), each player selects a number and adds it to the total. Once a number is used, it must be removed from the pool. The winner is the person whose number makes the total equal 31 exactly. Q12 Swap two numbers without using a third variable. Given an array (group) of numbers write all the possible sub groups of this group. Q14 Convert (integer) number in binary without loops. Q3,12 are similar , Q7 is simple & I know there answer For the Rest please Help Assuming that these questions are from an interview for a programming job, I must say that most of them are incredibly useless at finding a good programmer. Take Q3: The correct answer is: Why would anyone want to do that? Take Q10: You know the answer or you don't. If your name is Gödel or Turing, you might find a solution on your own, but otherwise this just tests some very obscure knowledge. I guess these questions are only used to check your reaction to a stressful situation (which is also an incredibly useless way at finding a good programmer). If I was given this list of questions, I would tell them that most of them are pointless and then examine Q11, because it is the only interesting one. Maybe a different response if you are desperate for a job. Back to top Siemel Naran Guest Posted: Sat Jun 26, 2004 11:02 pm    Post subject: Re: Programming Puzzle "Joona I Palaste" <palaste (AT) cc (DOT) helsinki.fi> wrote Quote: Jatinder <jsfromynr (AT) sancharnet (DOT) in> scribbled the following Q1 Write a "Hello World" program in 'C' without using a semicolon. Q2 Write a C++ program without using any loop (if, for, while etc) to print numbers from 1 to 100 and 100 to 1; Q3 C/C++ : Exchange two numbers without using a temporary variable. Done to death here on comp.lang.c. Not familiar with the first two. Q1, how? Is #define SEMICOLON ; valid? Q2, is recursion a valid answer? Or even just writing the numbers explicitly printf("1n2"), etc? For Q3 one can use ^= 3 times, though I wonder if this is faster than the usual one with a temp variable and 3 assignments on various platforms. Quote: Q4 C/C++ : Find if the given number is a power of 2. Easy with some bitwise arithmetic. x & (x-1) evaluates to zero if the number is an exact power of 2. Quote: Q5 C/C++ : Multiply x by 7 without using multiplication (*) operator. Easy peasy. Repeated addition will do the trick. Q6 C/C++ : Write a function in different ways that will return f(7) = 4 and f(4) = 7 int f(int x) { return x==4 ? 7 : x==7 ? 4 : 0; } Another is realize 4 = %100 and 7 = %111 in binary, so leave the leftmost bit on, and flip the other 2. Thus: return x ^ %11, or return x ^ 3. Quote: Q7 Remove duplicates in array You can't remove anything from an array. You can only modify the values of its elements. Fine, then how to replace the duplicates with NULL or the like, or move the elements one down so that { 1, 2, 1, 1, 4, 3 } becomes { 1, 2, 4, 3, anything, anything }? Quote: Q8 Finding if there is any loop inside linked list. Should be covered in any basic data structures course. Q9 Remove duplicates in an no key access database without using an array Impossible without access into a no key access database. What is Q9 about? Quote: Q10 Write a program whose printed output is an exact copy of the source. Needless to say, merely echoing the actual source file is not allowed. Google for "quine". Bizarre stuff! Quote: Q11 From a 'pool' of numbers (four '1's, four '2's .... four '6's), each player selects a number and adds it to the total. Once a number is used, it must be removed from the pool. The winner is the person whose number makes the total equal 31 exactly. This one is actually a full-blown game. Q12 Swap two numbers without using a third variable. And how is this any different from Q3? Given an array (group) of numbers write all the possible sub groups of this group. Search for the definition of a "power set". The algorithm shoudln't be too hard to figure out. Someone posted something like this in the C++ newsgroup. If you have 3 numbers 1, 2, 3 then make a number of 3 bits %000. Then just add 1 until you max out. So you get %000, %001, %010, %011, %100, %101, %110, %111. If the bit is 0 it means that number is not in the group and if the bit it 1 it means the number is in the group, so %001 is the group "1", and %011 is the group "1,2", and %101 is the group "1,3". In C++ you could maybe use std::bitset. But I think you could do it using recursion too. So f(3,1) prints the combinations "3,..." and f(3,0) prints combinations without the 3. The part in ... is the combinations with 2 numbers, so f(2,1) prints "2,..." and f(2,0) prints "...". The second ... is the combinations with 1 numbers, just "1" and "". Quote: Q14 Convert (integer) number in binary without loops. Already done here on comp.lang.c. How, if not recursion? Maybe even lookup tables, which I used to implement a fast lgdown(x) function which gives log to base 2 of x. Back to top Allan Bruce Guest Posted: Sun Jun 27, 2004 12:49 am    Post subject: Re: Programming Puzzle "Siemel Naran" <SiemelNaran (AT) REMOVE (DOT) att.net> wrote Quote: "Joona I Palaste" <palaste (AT) cc (DOT) helsinki.fi> wrote Jatinder <jsfromynr (AT) sancharnet (DOT) in> scribbled the following Q1 Write a "Hello World" program in 'C' without using a semicolon. Q2 Write a C++ program without using any loop (if, for, while etc) to print numbers from 1 to 100 and 100 to 1; Q3 C/C++ : Exchange two numbers without using a temporary variable. Done to death here on comp.lang.c. Not familiar with the first two. Q1, how? Is #define SEMICOLON ; valid? no, but consider this int main (void) { if (printf("Hello World")) {} if (exit(EXIT_SUCCESS)) {} } Allan Back to top CBFalconer Guest Posted: Sun Jun 27, 2004 2:12 am    Post subject: Re: Programming Puzzle Allan Bruce wrote: Quote: .... snip ... no, but consider this int main (void) { if (printf("Hello World")) {} if (exit(EXIT_SUCCESS)) {} } Illegal. No #include for prototype of variadic function, nor EXIT_SUCCESS value, and exit is a void function. The compiler should barf. I am trying to construct something that revolves around: if (printf("Hello ") - printf("Worldn")) {...} which statement could cause either "Hello World" or "WorldHello". -- Chuck F (cbfalconer (AT) yahoo (DOT) com) (cbfalconer (AT) worldnet (DOT) att.net) Available for consulting/temporary embedded and systems. <http://cbfalconer.home.att.net> USE worldnet address! Back to top Mabden Guest Posted: Sun Jun 27, 2004 6:49 am    Post subject: Re: Programming Puzzle "Christian Bau" <christian.bau (AT) cbau (DOT) freeserve.co.uk> wrote Quote: In article <22b2a6b6.0406261016.510e693b (AT) posting (DOT) google.com>, [email]jsfromynr (AT) sancharnet (DOT) in[/email] (Jatinder) wrote: Programming Puzzles Some companies certainly ask for these things. Specially Microsoft. Here are my favorite puzzles. Don't send me emails asking for the solutions. Q1 Write a "Hello World" program in 'C' without using a semicolon. Q2 Write a C++ program without using any loop (if, for, while etc) to print numbers from 1 to 100 and 100 to 1; Q3 C/C++ : Exchange two numbers without using a temporary variable. [snip] Quote: If I was given this list of questions, I would tell them that most of them are pointless and then examine Q11, because it is the only interesting one. Maybe a different response if you are desperate for a job. Maybe you would get the job for walking out... Back to top Siemel Naran Guest Posted: Sun Jun 27, 2004 7:16 am    Post subject: Re: Programming Puzzle "Mabden" <mabden (AT) sbc_global (DOT) net> wrote Quote: Maybe you would get the job for walking out... That might be too out of the box . Back to top Jerry Coffin Guest Posted: Sun Jun 27, 2004 7:49 am    Post subject: Re: Programming Puzzle [email]jsfromynr (AT) sancharnet (DOT) in[/email] (Jatinder) wrote in message news:<22b2a6b6.0406261016.510e693b (AT) posting (DOT) google.com>... [ ... ] Quote: Q1 Write a "Hello World" program in 'C' without using a semicolon. One obvious method (open to a number of variations) is: #include <stdio.h> int main() { if ( printf("Hello world")) {} } Quote: Q2 Write a C++ program without using any loop (if, for, while etc) to print numbers from 1 to 100 and 100 to 1; Almost anything you'd normally do with iteration can also be done with tail recursion. Quote: Q3 C/C++ : Exchange two numbers without using a temporary variable. This has come up about 4 weeks into every new semester for years, with a slightly lighter treatment on a quarterly basis. Quote: Q4 C/C++ : Find if the given number is a power of 2. There are many ways. Pick N as a power of 2, and compare it to N-1 and see if something doesn't occur to you. Quote: Q5 C/C++ : Multiply x by 7 without using multiplication (*) operator. One is to just add x together 7 times. Those of us who remember writing multiplication routines for old processors that didn't have multiply instructions can easily reduce that to (x<<2)|(x<<1)|x. Those who've studied Booth's algorithm might try (x<<3)-x, though without extra bits for the intermediate value, this can overflow. Quote: Q6 C/C++ : Write a function in different ways that will return f(7) = 4 and f(4) = 7 Obvious: int f(int x) { if ( x == 7) return 4; if ( x == 4) return 7; } Roughly as obvious is to use switch/case intsead. Using arrays, you can do things like: int f(int x) { int rets[] = { 4, 7}; return rets[x>>2]; } Or if you want to ensure defined results for inputs other than 4 or 7: int f(int x) { int rets[] = {4,7}; return rets[(x>>2)&1]; } If you want to get clever with boolean values, you could try: int f(int x) { return (x==7*4)+(x==4*7); } or: int f(int x) { rturn (x==7*4)|(x==4*7); } If you prefer strictly bit-wise manipulation, you might prefer: int f(int x) { return x ^ 3; } I'm sure there are more variations as well. Quote: Q7 Remove duplicates in array You can't really "remove" an element from an array, so this is poorly defined. If it was a C++ vector (for example) std::sort and std::unique would render it trivial, as would inserting the elements into an std::set, and then copying them back out. Doing it quickly while retaining the original order is a little more challenging. Quote: Q8 Finding if there is any loop inside linked list. One obvious way would be to create a set of pointers to nodes. Walk the list, inserting each node's address into the set. Quit when you reach a node with next == NULL (there's no loop) or a node whose address is already in the set (there's a loop). There's an alternative that saves memory, but basically destroys the list if it does contain a loop: as you walk the list, modify each 'next' pointer to point at the previous node. Eventually, you'll reach either a node with next==NULL, in which case there's no loop, or else you'll get back to the original head of the list (in which case there's a loop, and you've wreaked havoc on your list). If the list doesn't contain a loop, you can re-walk it, again reversing each pointer, to restore the original list. Better yet, just ensure the list is constructed sanely, and you'll know the answer up-front. Quote: Q10 Write a program whose printed output is an exact copy of the source. Needless to say, merely echoing the actual source file is not allowed. Much like Q3, but comes up a little further into the semster/quarter. Quote: Q11 From a 'pool' of numbers (four '1's, four '2's .... four '6's), each player selects a number and adds it to the total. Once a number is used, it must be removed from the pool. The winner is the person whose number makes the total equal 31 exactly. If I'm figuring this correctly, it's a pretty boring game. If I go first, I pick '1' on my first two moves, and you can't win. If I go second, I pick '2' on my first three moves, and you can't win. Tic-tac-toe quickly gets boring because neither player can win unless his opponent makes a mistake. This is even worse, because the same is true, BUT a player doesn't even have to look at what his opponent has done to avoid a mistake. The only challenge is ensuring that you take advantage when he does make a mistake, and (again, assuming I'm figuring things correctly) that should be quite trivial. Quote: Given an array (group) of numbers write all the possible sub groups of this group. Recursion is probably your friend on this one as well. Quote: Q14 Convert (integer) number in binary without loops. As mentioned wrt Q2, almost any iteration is trivially expressed as tail recursion. The wording doesn't make it clear whether this is supposed to be a conversion FROM binary or TO binary, but either is pretty easy to do recursively. -- Later, Jerry. The universe is a figment of its own imagination. Back to top Siemel Naran Guest Posted: Sun Jun 27, 2004 8:26 am    Post subject: Re: Programming Puzzle "Jerry Coffin" <jcoffin (AT) taeus (DOT) com> wrote Quote: Almost anything you'd normally do with iteration can also be done with tail recursion. What is "tail" recursion? Are there other types of recursion? Any the question says not to use loops. But to me, recursion is a loop, just expressed differently. Quote: Q5 C/C++ : Multiply x by 7 without using multiplication (*) operator. One is to just add x together 7 times. Those of us who remember writing multiplication routines for old processors that didn't have multiply instructions can easily reduce that to (x<<2)|(x<<1)|x. Those who've studied Booth's algorithm might try (x<<3)-x, though without extra bits for the intermediate value, this can overflow. Are these methods faster than x*7 on modern processors? Quote: Q6 C/C++ : Write a function in different ways that will return f(7) = 4 and f(4) = 7 If you want to get clever with boolean values, you could try: int f(int x) { return (x==7*4)+(x==4*7); } Huh? Quote: I'm sure there are more variations as well. Probably something with mod or %. Quote: Q7 Remove duplicates in array You can't really "remove" an element from an array, so this is poorly defined. If it was a C++ vector (for example) std::sort and std::unique would render it trivial, as would inserting the elements into an std::set, and then copying them back out. Doing it quickly while retaining the original order is a little more challenging. The sort method is O(N*lg(N)) + O(N) if we use comparison sort. But doing it in place without changing the order seems to be an O(N^2) algorithm, with the outer loop i running from [0, N) and the inner loop j running from [0, i). (Seems most people run the inner loop from [i+1, N) and then they run into problems of how to detect if you've not seen the element already.) Quote: Q8 Finding if there is any loop inside linked list. One obvious way would be to create a set of pointers to nodes. Walk the list, inserting each node's address into the set. Quit when you reach a node with next == NULL (there's no loop) or a node whose address is already in the set (there's a loop). There's an alternative that saves memory, but basically destroys the list if it does contain a loop: as you walk the list, modify each 'next' pointer to point at the previous node. Eventually, you'll reach either a node with next==NULL, in which case there's no loop, or else you'll get back to the original head of the list (in which case there's a loop, and you've wreaked havoc on your list). If the list doesn't contain a loop, you can re-walk it, again reversing each pointer, to restore the original list. Better yet, just ensure the list is constructed sanely, and you'll know the answer up-front. There's another. Have two iterators, first one pointing to first element, the second pointing to the second. The second one is the fast iterator and you increment it twice in each iteration. The first iterator is the slow iterator and you increment it once in each iteration. If the list is not circular the fast iterator will hit NULL at some point. If the list is circular the fast iterator will equal to the slow iterator at some point. Back to top Joona I Palaste Guest Posted: Sun Jun 27, 2004 9:05 am    Post subject: Re: Programming Puzzle Siemel Naran <SiemelNaran (AT) remove (DOT) att.net> scribbled the following on comp.lang.c: Quote: "Jerry Coffin" <jcoffin (AT) taeus (DOT) com> wrote in message news:b2e4b04.0406262349.465369ca (AT) posting (DOT) google.com... Almost anything you'd normally do with iteration can also be done with tail recursion. What is "tail" recursion? Are there other types of recursion? Tail recursion is first doing the computation, then recursing. Head recursion is the other way around. Quote: Any the question says not to use loops. But to me, recursion is a loop, just expressed differently. They're clearly different concepts. At least in C, recursion has a separate local scope for all levels, while looping reuses the same local scope for all iterations. Quote: Q6 C/C++ : Write a function in different ways that will return f(7) = 4 and f(4) = 7 If you want to get clever with boolean values, you could try: int f(int x) { return (x==7*4)+(x==4*7); } Huh? In C, the == operator returns 1 if the operands match or 0 if they don't. Go from there. -- /-- Joona Palaste (palaste (AT) cc (DOT) helsinki.fi) ------------- Finland -------- -- http://www.helsinki.fi/~palaste --------------------- rules! --------/ "The day Microsoft makes something that doesn't suck is probably the day they start making vacuum cleaners." - Ernst Jan Plugge Back to top Irrwahn Grausewitz Guest Posted: Sun Jun 27, 2004 9:08 am    Post subject: Re: Programming Puzzle "Siemel Naran" <SiemelNaran (AT) REMOVE (DOT) att.net> wrote: Quote: "Jerry Coffin" <jcoffin (AT) taeus (DOT) com> wrote in message news:b2e4b04.0406262349.465369ca (AT) posting (DOT) google.com... snip Q5 C/C++ : Multiply x by 7 without using multiplication (*) operator. snip If you want to get clever with boolean values, you could try: int f(int x) { return (x==7*4)+(x==4*7); } Huh? I'm pretty sure Jerry meant to write: return (x==7)*4 + (x==4)*7; Regards -- Irrwahn Grausewitz (irrwahn33 (AT) freenet (DOT) de) welcome to clc: http://www.ungerhu.com/jxh/clc.welcome.txt clc faq-list : http://www.faqs.org/faqs/C-faq/faq/ clc OT guide : http://benpfaff.org/writings/clc/off-topic.html Back to top Irrwahn Grausewitz Guest Posted: Sun Jun 27, 2004 9:14 am    Post subject: Re: Programming Puzzle Joona I Palaste <palaste (AT) cc (DOT) helsinki.fi> wrote: Quote: Siemel Naran <SiemelNaran (AT) remove (DOT) att.net> scribbled the following on comp.lang.c: "Jerry Coffin" <jcoffin (AT) taeus (DOT) com> wrote in message news:b2e4b04.0406262349.465369ca (AT) posting (DOT) google.com... Q6 C/C++ : Write a function in different ways that will return f(7) = 4 and f(4) = 7 If you want to get clever with boolean values, you could try: int f(int x) { return (x==7*4)+(x==4*7); } Huh? In C, the == operator returns 1 if the operands match or 0 if they don't. Go from there. Now f returns 2 if x equals 28, or 0 otherwise. Great solution. ;-) Regards -- Irrwahn Grausewitz (irrwahn33 (AT) freenet (DOT) de) welcome to clc: http://www.ungerhu.com/jxh/clc.welcome.txt clc faq-list : http://www.faqs.org/faqs/C-faq/faq/ clc OT guide : http://benpfaff.org/writings/clc/off-topic.html Back to top Joona I Palaste Guest Posted: Sun Jun 27, 2004 9:15 am    Post subject: Re: Programming Puzzle Irrwahn Grausewitz <irrwahn33 (AT) freenet (DOT) de> scribbled the following on comp.lang.c: Quote: "Siemel Naran" <SiemelNaran (AT) REMOVE (DOT) att.net> wrote: "Jerry Coffin" <jcoffin (AT) taeus (DOT) com> wrote in message news:b2e4b04.0406262349.465369ca (AT) posting (DOT) google.com... snip Q5 C/C++ : Multiply x by 7 without using multiplication (*) operator. snip If you want to get clever with boolean values, you could try: int f(int x) { return (x==7*4)+(x==4*7); } Huh? I'm pretty sure Jerry meant to write: return (x==7)*4 + (x==4)*7; Dang! I didn't spot that in my original reply. Jerry's original code is equivalent to return (x==2+(x==2, which will return 2 if x==28 but 0 if not. -- /-- Joona Palaste (palaste (AT) cc (DOT) helsinki.fi) ------------- Finland -------- -- http://www.helsinki.fi/~palaste --------------------- rules! --------/ "You can pick your friends, you can pick your nose, but you can't pick your relatives." - MAD Magazine Back to top Joona I Palaste Guest Posted: Sun Jun 27, 2004 9:17 am    Post subject: Re: Programming Puzzle Irrwahn Grausewitz <irrwahn33 (AT) freenet (DOT) de> scribbled the following on comp.lang.c: Quote: Joona I Palaste <palaste (AT) cc (DOT) helsinki.fi> wrote: Siemel Naran <SiemelNaran (AT) remove (DOT) att.net> scribbled the following on comp.lang.c: "Jerry Coffin" <jcoffin (AT) taeus (DOT) com> wrote in message news:b2e4b04.0406262349.465369ca (AT) posting (DOT) google.com... Q6 C/C++ : Write a function in different ways that will return f(7) = 4 and f(4) = 7 If you want to get clever with boolean values, you could try: int f(int x) { return (x==7*4)+(x==4*7); } Huh? In C, the == operator returns 1 if the operands match or 0 if they don't. Go from there. Now f returns 2 if x equals 28, or 0 otherwise. Great solution. Yes, I noticed it myself later, as you can see. In my defense, it was Jerry who wrote the incorrect code, I just failed to correct it... =) -- /-- Joona Palaste (palaste (AT) cc (DOT) helsinki.fi) ------------- Finland -------- -- http://www.helsinki.fi/~palaste --------------------- rules! --------/ "And according to Occam's Toothbrush, we only need to optimise the most frequent instructions." - Teemu Kerola Back to top Display posts from previous: All Posts1 Day7 Days2 Weeks1 Month3 Months6 Months1 Year Oldest FirstNewest First         C++Talk.NET Forum Index -> C++ language (comp.lang.c++) All times are GMT Goto page 1, 2, 3 ... 17, 18, 19  Next Page 1 of 19   Jump to: Select a forum C/C++----------------C LanguageC Language (Moderated)C++ Language (Moderated)C++ language (comp.lang.c++)C++ language, library and standards Non-English C/C++ Newsgroups----------------C++ (German)C++ (French)  You cannot post new topics in this forum You cannot reply to topics in this forum You cannot edit your posts in this forum You cannot delete your posts in this forum You cannot vote in polls in this forum Powered by phpBB © 2001, 2006 phpBB Group SEO toolkit © 2004-2006 webmedic.