python/TangDou/AcWing/poj-1182.cpp

#include <bits/stdc++.h>

using namespace std;

const int N = 50005;

int p[N];
int d[N];    // 0 ： 同类 1：吃 2：被吃

// 分析：https://blog.csdn.net/yjr3426619/article/details/82315133
// A吃B B吃C ==> A被C吃     Relation(a,c) = Relation(a,b)+Relation(b,c)
// A被B吃 B被C吃 ==> A吃C Relation(a,c) = (Relation(a,b)+Relation(b,c))%3
int find(int x) {
    if (x != p[x]) {
        int t = p[x];
        p[x] = find(p[x]);
        d[x] = (d[x] + d[t]) % 3;
    }
    return p[x];
}

int main() {
    //输入+输出重定向
    freopen("../AcWing/N5/poj-1182.txt", "r", stdin);
    int n, k;

    cin >> n >> k;
    int ans = 0;
    for (int i = 1; i <= n; i++) {
        p[i] = i;
    }
    while (k--) {
        int relation, x, y;
        scanf("%d%d%d", &relation, &x, &y);
        if (x > n || y > n || (relation == 2 && x == y)) {
            ans++;
        } else {
            int fx = find(x);
            int fy = find(y);
            if (fx == fy) {
                if ((relation - 1) != ((d[x] - d[y] + 3) % 3))
                    ans++;
            } else {
                p[fx] = fy;
                d[fx] = (-d[x] + relation - 1 + d[y]) % 3;
            }
        }
    }
    cout << ans;
    //关闭文件
    fclose(stdin);
    return 0;
}