Codeforces 875F Royal Questions (看题解)

Posted 2021-02-12 cjlhy

我还以为是什么板子题呢。。。

我们把儿子当做点， 公主当做边， 然后就是求边权值最大基环树森林。

#include<bits/stdc++.h>
#define LL long long
#define fi first
#define se second
#define mk make_pair
#define PLL pair<LL, LL>
#define PLI pair<LL, int>
#define PII pair<int, int>
#define SZ(x) ((int)x.size())
#define ull unsigned long long
using namespace std;

const int N = 2e5 + 7;
const int inf = 0x3f3f3f3f;
const LL INF = 0x3f3f3f3f3f3f3f3f;
const int mod = 1e9 + 7;
const double eps = 1e-8;

int n, m, ans, a[N], b[N], w[N], fa[N], id[N];
bool vis[N];

int getRoot(int x) {
    return fa[x] == x ? x : fa[x] = getRoot(fa[x]);
}

bool cmp(const int&a, const int& b) {
    return w[a] > w[b];
}

int main(){
    scanf("%d%d", &n, &m);
    for(int i = 1; i <= m; i++)
        scanf("%d%d%d", &a[i], &b[i], &w[i]);
    for(int i = 1; i <= m; i++) id[i] = i;
    for(int i = 1; i <= n; i++) fa[i] = i;
    sort(id + 1, id + 1 + m, cmp);
    for(int i = 1; i <= m; i++) {
        int p = id[i];
        int x = getRoot(a[p]);
        int y = getRoot(b[p]);
        if(x != y && (!vis[x] || !vis[y])) {
            ans += w[p];
            if(!vis[x]) fa[x] = y;
            else fa[y] = x;
        } else if(!vis[x]){
            ans += w[p];
            vis[x] = true;
        }
    }
    printf("%d
", ans);
    return 0;
}
/*
*/