POJ - 2492 A Bug‘s Life（带权并查集板子）

题目链接

思路:
带权并查集板子题，将种类分为两类，对2取余为0的一类，取余为1的一类，
对于每组输入数据维护带权并查集关系，遇到与前面相悖的就直接flag更新，这组数据后面的就不用考虑了。

代码：

#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#define fastio ios::sync_with_stdio(false), cin.tie(NULL), cout.tie(NULL)
#define debug(a) cout << "debug : " << (#a) << " = " << a << endl

using namespace std;

typedef long long ll;
typedef pair<int, int> PII;

const int N = 2010;
const int INF = 0x3f3f3f3f;
const double eps = 1e-6;
const int mod = 998244353;

int n, m;
int f[N], d[N];
int find(int x)
{
    if (x != f[x])
    {
        int u = find(f[x]);
        d[x] += d[f[x]];
        f[x] = u;
    }
    return f[x];
}

int main()
{
    int T;
    cin >> T;
    for (int j = 1; j <= T; j++)
    {
        scanf("%d%d", &n, &m);
        for (int i = 1; i <= n; i++)
            f[i] = i, d[i] = 0;
        bool flag = false;
        while (m--)
        {
            int x, y;
            scanf("%d%d", &x, &y);
            if (flag)
                continue;
            int f1 = find(x), f2 = find(y);
            if (f1 != f2)
            {
                f[f1] = f2;
                d[f1] = d[y] + 1 - d[x];
                while (d[f1] < 0)
                    d[f1] += 2;
            }
            else
            {
                if (d[x] % 2 == d[y] % 2)
                    flag = true;
            }
        }
        printf("Scenario #%d:\n", j);
        if (flag)
            printf("Suspicious bugs found!\n");
        else
            printf("No suspicious bugs found!\n");
        printf("\n");
    }
    return 0;
}