hihoCoder 数组重排

 1 #include <bits/stdc++.h>
 2 
 3 using namespace std;
 4 const int maxn = 100 + 10;
 5 typedef long long int64;
 6 
 7 int n;
 8 int p[maxn];
 9 
10 int64 cal(int a){
11       int t = p[a], cnt = 1;
12       while(t != a){
13             t = p[t];
14             cnt++;
15       }
16 
17       return (int64)cnt;
18 }
19 
20 int64 gcd(int64 a, int64 b){
21       if( b == 0 )
22             return a;
23       return gcd(b, a%b);
24 }
25 
26 int main(void){
27       scanf("%d", &n);
28 
29       for(int i = 1; i <= n; ++i){
30             scanf("%d", &p[i]);
31       }
32 
33       int64 a = cal(1);
34       int64 ans = a;
35       for(int i = 2; i <= n; ++i){
36            int64 b = cal(i);
37            ans = ans * b / gcd(ans, b);
38       }
39 
40       printf("%d\n", (int)ans);
41 
42       return 0;
43 }