A-B-C-
https://ac.nowcoder.com/acm/contest/322/D
題解:亂搞,有就行了
/* *@Author: STZG *@Language: C++ */ #include <bits/stdc++.h> #include<iostream> #include<algorithm> #include<cstdlib> #include<cstring> #include<cstdio> #include<string> #include<vector> #include<bitset> #include<queue> #include<deque> #include<stack> #include<cmath> #include<list> #include<map> #include<set> //#define DEBUG #define RI register int using namespace std; typedef long long ll; //typedef __int128 lll; const int N=100000+10; const int MOD=1e9+7; const double PI = acos(-1.0); const double EXP = 1E-8; const int INF = 0x3f3f3f3f; int t,n,m,k,q,ans; int a[N]; char str; int main() { #ifdef DEBUGfreopen("input.in", "r", stdin);//freopen("output.out", "w", stdout); #endifscanf("%d",&n);for(int i=1;i<=n;i++){scanf("%d",&a[i]);}for(int i=1;i<=n;i++){if(a[a[a[i]]]==i){cout << "YES" << endl;return 0;}}cout << "NO" << endl;//cout << "Hello world!" << endl;return 0; }?
總結