Need help with this programming problem involving flipping coins
Im trying to solve the flipping coins problem on codechef.com (http://www.codechef.com/problems/FLIPCOIN/) My code is in C, and i te开发者_运维技巧sted it using gcc v4.4.3 on my machine running Linux,and my program works for the sample input provided. However, on uploading to the judge i get the message "Wrong Answer". In my program i represent the flipping of coins by the toggling of bits.I think my algorithm is correct,and im not able to come up with a case where it would fail. Below is my code. Any help would be really appreciated.
Thank You.
#include <stdio.h>
long int n=0,temp,number_of_coins,number_of_inputs,bit_mask;
long int number_of_ones(long int i) //Return the number of bits set
{
return __builtin_popcountl(i);
}
int main(void)
{
long int ctr,lower,upper,length;
int op;
scanf("%ld %ld",&number_of_coins,&number_of_inputs);
length = number_of_coins-1;
for(ctr = 0 ; ctr < number_of_inputs;ctr++) //Main loop
{
scanf("%d %ld %ld",&op,&lower,&upper);
bit_mask = ((1 << length-lower+1)-1) & ~((1 << length-upper)-1);
if(op == 0)
{
n ^= bit_mask ; //Toggle the bits in the range lower to upper
}
else
{
temp = n;
temp &= bit_mask;
printf("%ld\n",number_of_ones(temp)); //Print number of bits set
}
}
return 0;
}
Since you use a bit sequence stored in a long int
to represent the coins, your code won't work with more than 32 coins (or however many bits are in a long
). The site specifies that there can be up to 100000 coins though.
There is probably a problem with the CodeChef method of checking the results, as i have gotten the same answer as well. There is not a problem with your code.
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