uva11549 Floyd判圈法

题意：

给两个数n, k,每次将k平方取k的前n位，问所有出现过的数的最大值

原来这就是floyd判圈法。。

#include<cstdio>
#include<cstdlib>
#include<algorithm>
#include<iostream>
#include<cstring>
#include<string>

template<typename Q> Q read(Q& x) {
    static char c;
    static bool f;
    for(f = 0; c = getchar(), !isdigit(c); ) if(c == '-') f = 1;
    for(x = 0; isdigit(c); c = getchar()) x = x * 10 + c - '0';
    if(f) x = -x; return x;
}
template<typename Q> Q read() {
    static Q x; read(x); return x;
}

typedef long long LL;

int next(int n, int x) {
    LL x2 = (LL) x * x;
    int len = 0;
    for(LL t = x2; t; t /= 10) len++;
    if(len > n) for(int t = len - n; t--; x2 /= 10);
    return x2;
}

int main() {
#ifdef DEBUG
    freopen("in.txt", "r", stdin);
    freopen("out.txt", "w", stdout);
#endif
    
    int T = read<int>();
    while(T--) {
        int n = read<int>(), k = read<int>();
        int ans = k, k1 = k, k2 = k;
        do {
            k1 = next(n, k1);
            k2 = next(n, k2); ans = std::max(ans, k2);
            k2 = next(n, k2); ans = std::max(ans, k2);
        }while(k1 != k2);
        printf("%d
", ans);
    }
    
    return 0;
}