codechef AMSGAME1 - "subtraction game 1" solution

codechef AMSGAME1 - "subtraction game 1": http://www.codechef.com/problems/AMSGAME1

editorial: http://discuss.codechef.com/questions/10494/amsgame1-editorial

codechef AMSGAME1 - "subtraction game 1" solution: http://ideone.com/JndiG1

#include <iostream>

#include <cstdio>

using namespace std;

unsigned int gcd(unsigned int u, unsigned int v) {

if(u==v) return u;

if(u==0) return v;

if(v==0) return u;

if(~u & 1) {

if(v & 1) return gcd(u>>1, v);

else return gcd(u>>1, v>>1) <<1;

}

if(~v & 1) return gcd(u, v>>1);

if(u>v) return gcd((u-v)>>1, v);

return gcd((v-u)>>1, u);

}

int main() {

int t, n, c[1005], a, b;

scanf("%d", &t);

while(t--) {

scanf("%d", &n);

if(n==1) { scanf("%d", &a); printf("%d\n", a); }

if(n==2) { scanf("%d %d", &a, &b); printf("%d\n", gcd(a, b)); }

if(n>2) {

for(int i=0; i<2; i++)  {

scanf("%d %d", &a, &b); a=gcd(a, b); break;

}

for(int i=2; i<n; i++) {

scanf("%d", &b); a=gcd(a, b); 

}

printf("%d\n", a);

}

}

return 0;

}

note: i used binary gcd here.