View Code of Problem 131

#include<bits/stdc++.h>
using namespace std;
int main() {
	int n,m,a,b,i,j,k;
	while (cin>>n>>m){
		int s[100][100] = {};
		for (i = 0; i < m; i++) {
			cin>>a>>b;
			s[b][a] = 1;//有先b再a的关系存在 
		}
		for (k = 1; k <= n; k++) {
			for (i = 1; i <= n; i++) {
				for (j = 1; j <= n; j++) {
					if (s[i][k] && s[k][j]) {
						s[i][j] = 1;
					}
				}
			}
		}
		int flag = 1;
		for (i = 1; i <= n; i++) { 
			for (j = 1; j <= n; j++) {
				if (s[i][j] && s[j][i]) {
					flag = 0;
					break;
				}
			}
		}
		if (flag) {
			printf("RIGHT\n");
		}
		else {
			printf("ERROR\n");
		}
	}
}