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。。

 1 #include<cstdio>
 2 #include<cstdlib>
 3 #include<algorithm>
 4 #include<iostream>
 5 #include<cstring>
 6 #include<string>
 7 
 8 template<typename Q> Q read(Q& x) {
 9     static char c;
10     static bool f;
11     for(f = 0; c = getchar(), !isdigit(c); ) if(c == '-') f = 1;
12     for(x = 0; isdigit(c); c = getchar()) x = x * 10 + c - '0';
13     if(f) x = -x; return x;
14 }
15 template<typename Q> Q read() {
16     static Q x; read(x); return x;
17 }
18 
19 typedef long long LL;
20 
21 int next(int n, int x) {
22     LL x2 = (LL) x * x;
23     int len = 0;
24     for(LL t = x2; t; t /= 10) len++;
25     if(len > n) for(int t = len - n; t--; x2 /= 10);
26     return x2;
27 }
28 
29 int main() {
30 #ifdef DEBUG
31     freopen("in.txt", "r", stdin);
32     freopen("out.txt", "w", stdout);
33 #endif
34     
35     int T = read<int>();
36     while(T--) {
37         int n = read<int>(), k = read<int>();
38         int ans = k, k1 = k, k2 = k;
39         do {
40             k1 = next(n, k1);
41             k2 = next(n, k2); ans = std::max(ans, k2);
42             k2 = next(n, k2); ans = std::max(ans, k2);
43         }while(k1 != k2);
44         printf("%d
", ans);
45     }
46     
47     return 0;
48 }