题解集合

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原题链接

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题解

代码+注释

#include <cstring>
#include <iostream>
#include <algorithm>

using namespace std;

const int N = 2010, M = 10010;

int n , m;
struct Edge
{
    int a,b,w;
    bool operator< (const Edge &t) const
    {
        return w < t.w;
    }
}e[M];
int p[N];

int find(int x)
{
    if(p[x] != x) p[x] = find(p[x]);
    return p[x];
}

int main()
{
    cin >> n >> m;
    for(int i = 1;i <= n;i ++) p[i] = i;

    int res = 0,k = 0;
    for(int i = 0;i < m; i++)
    {
        int t,a,b,w;
        cin >> t >> a >> b >> w;
        if(t == 1)//缩点
        {
            res += w;
            p[find(a)] = find(b);
        }
        else e[k ++] = {a,b,w};
    }

        sort(e,e + k);

//最小生成树

        for(int i = 0;i < k;i ++)
        {
            int a = find(e[i].a) , b = find(e[i].b), w = e[i].w;
            if(a != b)
            {
                p[a] = b;
                res += w;
            }

        }

    cout << res << endl;

    return 0;
}