PS: 开始我用二分染色做了一下这道题目, 今天再用并查集解此题。 关键是表示二元关系。

#include <iostream>
#include <cstdio>
#include <algorithm>
#include <cstring>
using namespace std;
const int maxn = 2010;

int f[maxn];
int mark[maxn];
int n, m;
bool flag;
//Accepted	676K	750MS	G++	1230B	2014-05-07 20:02:20
int getFather(int x) {
    if(x==f[x]) return x;
    int t = f[x];
    f[x] = getFather(f[x]);
    mark[x] = (mark[x]+mark[t])%2;
    return f[x];
}

void make(int a, int b) {
    int t1 = getFather(a);
    int t2 = getFather(b);
    if(t1 != t2) {
        f[t1] = t2;
        if((mark[a]+mark[b])%2==0) {
            mark[t1] = 1;
        }
    }
    else {
        if(mark[a]==mark[b]) {
            flag = false;
        }
    }
}

int main()
{
    int x, y;
    int T;
    scanf("%d", &T);
    for(int t = 1; t <= T; t++) {
        scanf("%d%d", &n, &m);
        memset(mark, 0, sizeof(mark));
        flag = true;
        for(int i = 1; i <= n; i++) f[i] = i;
        for(int i = 0; i < m; i++) {
            scanf("%d%d", &x, &y);
            make(x, y);
        }
        printf("Scenario #%d:\n", t);
        if(flag) {
            printf("No suspicious bugs found!\n");
        } else {
            printf("Suspicious bugs found!\n");
        }
        printf("\n");
    }
    return 0;
}