HDU 1829 A Bug's Life（种类并查集）

原创

aozil_yang 2023-05-15 01:03:09 ©著作权

文章标签 种类并查集结点 #include Java 文章分类 办公效率

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题意：

给你n 个人，m 个操作，每个操作告诉你两个人不是一个性别的，问你能否给所有人分成两组不冲突。

思路：

加权并查集取模变成种类并查集。

好不爽，个人赛时竟然花费了一小时在一道简单的种类并查集上，于是就找了几个类似的水一水= =！

我们记录每个结点父节点时，在开一个数组a，记录这个结点到根结点的距离。

这样如果一个操作中的两个人在一个连通块时，那么只需要判断它们的距离是否是一个奇数另一个是偶数即可。相同的话就冲突了。

如果不在一格连通块里直接合并重新算一下距离取模即可。

#include <cstdio>
#include <cstring>
#include <algorithm>
using namespace std;

int T;
int a[2333];
int fa[2333];

int find(int x){
    if (fa[x] == x) return x;
    int f = fa[x];
    fa[x] = find(fa[x]);
    a[x] = (a[x] + a[f]) % 2;
    return fa[x];
}

int main(){
    int ks = 0;
    scanf("%d",&T);
    while(T--){
        int n,m;
        scanf("%d %d", &n, &m);
        for (int i = 1; i <= n; ++i) a[i]=0,fa[i] = i;
        int flag = 0;
        for (int i = 0 ; i < m; ++i){
            int x,y;
            scanf("%d %d",&x, &y);
            if (flag)continue;
            int fx = find(x), fy = find(y);
            if (fx == fy){
                if (a[x] == a[y]) flag = 1;
            }
            else {
                fa[fx] = fy;
                a[fx] = (a[y] - a[x] + 2 + 1) % 2;
            }

        }
        printf("Scenario #%d:\n",++ks);
        if (flag)puts("Suspicious bugs found!\n");
        else puts("No suspicious bugs found!\n");
    }

    return 0;
}

A Bug's Life

Time Limit: 15000/5000 MS (Java/Others) Memory Limit: 32768/32768 K (Java/Others)
Total Submission(s): 14629 Accepted Submission(s): 4777

Problem Description

Background
Professor Hopper is researching the sexual behavior of a rare species of bugs. He assumes that they feature two different genders and that they only interact with bugs of the opposite gender. In his experiment, individual bugs and their interactions were easy to identify, because numbers were printed on their backs.

Problem
Given a list of bug interactions, decide whether the experiment supports his assumption of two genders with no homosexual bugs or if it contains some bug interactions that falsify it.

Input

The first line of the input contains the number of scenarios. Each scenario starts with one line giving the number of bugs (at least one, and up to 2000) and the number of interactions (up to 1000000) separated by a single space. In the following lines, each interaction is given in the form of two distinct bug numbers separated by a single space. Bugs are numbered consecutively starting from one.

Output

The output for every scenario is a line containing "Scenario #i:", where i is the number of the scenario starting at 1, followed by one line saying either "No suspicious bugs found!" if the experiment is consistent with his assumption about the bugs' sexual behavior, or "Suspicious bugs found!" if Professor Hopper's assumption is definitely wrong.

Sample Input