Checking whether two numbers are permutation of each other?

Question

Given two numbers a, b such that 1 <= a , b <= 10000000000 (10^10). My problem is to check whether the digits in them are permutation of each other or not. What is the fas

Answer 1

a and b are anagrams if they have the same number of each digit. So basically the fastest way seems to be, counting the digits for a and b:

int c[10]={0,0,0,0,0,0,0,0,0,0}

while (a) { c[a%10]++; a/=10; }
while (b) { c[b%10]--; b/=10; }

int res=1;
for (int i=0;i<10;i++) res &= c[i]==0;
printf(res?"yes":"no");