kuangbin_UnionFind J (POJ 2492)

加权并查集mod2模板 本体的难点是bug的释义(笑)

#include <iostream>
#include <string>
#include <cstdio>
#include <cmath>
#include <cstring>
#include <queue>
#include <map>
#include <set>
#include <algorithm>
using namespace std;

int father[5005],sum[5005];
int find(int x)
{
    if(father[x] != x) {
        int tmp = father[x];
        father[x] = find(tmp);
        sum[x] = (sum[x] + sum[tmp]) % 2;
    }
    return father[x];
}
void merge(int x,int y)
{
    int tx = find(x);
    int ty = find(y);
    //printf("x = %d y = %d
tx = %d ty = %d
", x, y, tx, ty);
    if(tx == ty) return;
    father[tx] = ty;
    //printf("father(1) = %d
",father[1]);
    sum[tx] = (sum[x] - sum[y] + 1) % 2;
    return;
}
int main()
{
    int t;
    scanf("%d",&t);
    for(int kase = 1; kase <= t; kase++)
    {
        int n, m;
        bool flag = true;
        scanf("%d%d", &n, &m);
        //Initiate
        for(int i = 0; i <= n; i++)
        {
            father[i] = i;
            sum[i] = 0;
        }
        while(m--)
        {
            int a, b;
            scanf("%d%d", &a, &b);
            if(find(a) == find(b))  
            {
                if(sum[a] != (sum[b] + 1) % 2){
                    //printf("a = %d b = %d
", a, b);
                    flag = false;  
                }
            }  
            else  
                merge(a, b);  
        }
        printf("Scenario #%d:
", kase);
        if(flag) printf("No suspicious bugs found!

");
        else printf("Suspicious bugs found!

");
    }
    return 0;
}