洛谷 p3366 最小生成树

想了解什么是最小生成树可以参考网址：网址

这个题就是运用并查集进行筛选；

先排序；

然后就筛选

#pragma GCC optimize(2)

#include 

#define maxn 200005

typedef long long ll;

using namespace std;

ll b[maxn];
struct node
{
    ll from;
    ll to;
    ll len;
}
a[maxn];

bool cmp(node a,node b)
{
    return a.len < b.len;
}

ll find(ll x)
{
    return b[x] == x ? x : b[x] = find(b[x]);
}
int main()
{
    ios::sync_with_stdio(0);
    cin.tie(0),cout.tie(0);

    ll n,m;
    cin >> n >> m;
    for(int i = 1; i <= n; i ++)
    {
        b[i] = i;
    }

    for(int i = 1; i <= m; i ++)
    {
        cin >> a[i].from >> a[i].to >> a[i].len;
    }
    sort(a+1,a+m+1,cmp);

    ll sum = 0,total = 0;
    for(int i = 1; i <= m; i ++)
    {
        ll fx = find(a[i].from);
        ll fy = find(a[i].to);
        if(total == n - 1)break;
        if(fx == fy)continue;
        else
        {
            b[fx] = fy;
            sum += a[i].len;
            total++;
        }
    }
    if(total == n - 1)cout << sum << endl;
    else cout << "orz" << endl;

    return 0;
}