hdu2817 A sequence of numbers (a^i mod n)

题目链接：http://acm.hdu.edu.cn/showproblem.php?pid=2817

#include <stdio.h>#define MOD  200907_int64 pow_mod(_int64 a,_int64 k){_int64 temp=1;while(k){if(k&1)temp=(temp*a)%MOD;a=(a*a)%MOD;k>>=1;}return temp;}int main(){_int64 a,b,c,k,ans,q;int test;scanf("%d",&test);while(test--){scanf("%I64d %I64d %I64d %I64d",&a,&b,&c,&k);if(b+b==a+c){ans=(a%MOD+((k-1)%MOD*((b-a)%MOD))%MOD)%MOD;printf("%I64d\n",ans);}else{q=b/a;ans=(pow_mod(q,k-1)*(a%MOD))%MOD;printf("%I64d\n",ans);}}return 0;}