prim 堆优化

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#include <iostream>#include <algorithm>#include <cstdio>#include <cstring>#include <vector>#include <string>#include <queue>using namespace std;const int MAXN = 1005;const int INF = 1 << 30;struct Node {int u, w;friend bool operator<(const Node& a, const Node& b){return a.w > b.w;}Node() {}Node(int uu, int ww) : u(uu), w(ww) {}};vector<Node> graph[MAXN];int prim(int n){bool vis[MAXN]{ false };priority_queue<Node> q;vis[1] = true;for (int i = 0; i < graph[1].size(); ++i)q.push(graph[1][i]);int ans = 0;int cnt = 0;Node t;while (cnt < n - 1){t = q.top();q.pop();if (vis[t.u])continue;vis[t.u] = true;ans += t.w;++cnt;int n = t.u;for (int i = 0; i < graph[n].size(); ++i)if (!vis[graph[n][i].u])q.push(graph[n][i]);}return ans;}int main(void){int n, m, u, v, w;scanf("%d%d", &n, &m);while (m--){scanf("%d %d %d", &u, &v, &w);graph[u].push_back(Node(v, w));graph[v].push_back(Node(u, w));}cout << prim(n) << endl;return 0;}

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