UVA 11582 Colossal Fibonacci Numbers!

题目链接  http://acm.hust.edu.cn/vjudge/problem/41990

题意：让你求斐波纳契数列的第 a^b项 模n的结果(1<=n<=1000) 

预处理求出n分别为1-1000时斐波那契模数列的周期，不同的n值都会对应一个周期

之后求出a^b是周期中第几个

longlong会爆  要用unsigned longlon

#include <iostream>
#include <algorithm>
#include <cstdio>
#include <cstring>
#include <queue>
#include <vector>
#include <cmath>
#include <stack>
#include <map>
#include <set>
#define pi acos(-1)
#define LL long long
#define ULL unsigned long long
#define INF 0x3f3f3f3f
using namespace std;
typedef pair<int, int> P;
const int maxn = 1e5 + 5;

vector<int>fib[1005];
int qpow(ULL x, ULL n, int mod)
{
int res = 1;
while (n){
if (n & 1) res = (int)(res * x % mod);
x = x * x % mod;
n >>= 1;
}
return res;
}
void pre_process()
{
for (int m = 2; m <= 1000; m++){
fib[m].push_back(0);
fib[m].push_back(1);
for (int i = 2; ; i++){
fib[m].push_back( (fib[m][i-1] + fib[m][i-2]) % m );
if (fib[m][i] == 1 && fib[m][i-1] == 0)
break;
}
int cnt = fib[m].size(); //多了1和0两个数
fib[m].resize(cnt-2);
}
}
int main(void)
{
// freopen("C:\\Users\\wave\\Desktop\\NULL.exe\\NULL\\in.txt","r", stdin);
ULL a, b;
int n, T, dex;
pre_process();
cin >> T;
while(T--)
{
scanf("%llu %llu %d", &a, &b, &n);
if (a == 0 || n == 1)
printf("0\n");
else {
int mod = fib
.size();
dex = qpow(a%mod, b, mod); // a要先mod一下 不然会爆
printf("%d\n", fib
[dex]);
}
}

return 0;
}