poj 2144 Leaky Cryptography

#include <iostream>using namespace std;int num[10],ans,C;void cal(int p, int s) {    if(p==32) return;    int sum=s,i;    for(i=0;i<8;i++) sum+=(num[i]>>p)&1;    if((sum&1)!=((num[8]>>p)&1)) {        ans|=1<<p;        sum=s;        for(i=0;i<8;i++) sum+=((num[i]>>p)&1)^1;    }    cal(p+1,sum/2);}int main(){for(scanf("%d",&C);C--;){for(int i=0;i<9;i++) scanf("%x",&num[i]);ans=0;cal(0,0);printf("%xn",ans);}    return 0;}