Modules(最小树形图)

Modules

题目链接：here

朱刘算法

#include <bits/stdc++.h>
using namespace std;
#define LL long long
const int inf = 0x3f3f3f3f;
const int maxn = 3010;
const int maxe = 3010 * 2;
struct Edge{
    int u, v, w;
    Edge(int u = 0, int v = 0, int w = 0) : u(u), v(v), w(w) {}
}e[maxe];

int  pre[maxn], id[maxn], vis[maxn];
LL in[maxn];

 LL Dir_MST(int n, int m){
    int rt = 0;
    LL ans = 0;
    for(int i = 1; i <= n; i++)  e[m++] = Edge(rt, i, 0);
    n++;
    int cnt = m;
    while(true) {
        for(int i = 0; i < n; i++) in[i] = -inf;
        for(int i = 0; i < cnt; i++) {
            int u = e[i].u, v = e[i].v, w = e[i].w;
            if(w > in[v] && u != v) {
                in[v] = w;
                pre[v] = u;
            }
        }
        int cntnode = 0;
        memset(vis, -1, sizeof(vis));
        memset(id, -1, sizeof(id));
        in[rt] = 0;
        for(int i = 0; i < n; i++){
            ans = ans + in[i];
            int v = i;
            while(vis[v] != i && v != rt && id[v] == -1) {
                vis[v] = i;
                v = pre[v];
            }
            if(id[v] == -1 && v != rt){
                for(int u = pre[v]; u != v; u = pre[u]) id[u] = cntnode;
                id[v] = cntnode++;
            }
        }
        if(cntnode == 0) break;
        for(int i = 0; i < n; i++){
            if(id[i] == -1) id[i] = cntnode++;
        }
        for(int i = 0; i < cnt; i++){
            int v = e[i].v;
            e[i].u = id[e[i].u];
            e[i].v = id[e[i].v];
            if(e[i].u != e[i].v) e[i].w -= in[v];
        }
        n = cntnode;
        rt = id[rt];
    }
    return ans;
}

int main(){
    int t, n, m;
    //freopen("in.txt", "r", stdin);
    scanf("%d", &t);
    while(t--) {
        scanf("%d %d", &n, &m);
        LL ans = 0;
        int x;
        for(int i = 0; i < n; i++) {
            scanf("%d", &x);
            ans += x;
        }
        int u, v, w;
        for(int i = 0; i < m; i++){
            scanf("%d %d %d", &u, &v, &w);
            e[i] = Edge(v, u, w);
        }
        printf("%lld
", Dir_MST(n, m) + ans);
    }
    return 0;
}