859. Kruskal算法求最小生成树

https://www.acwing.com/problem/content/submission/code_detail/7029702/

AcWing/859/859.cpp

@@ -0,0 +1,42 @@
+#include <bits/stdc++.h>
+
+using namespace std;
+
+int n, m, fa[100005], res, cnt;
+struct node {
+    int u, v, w;
+
+    bool operator<(const node x) const {
+        return w < x.w;
+    }
+} g[200005];
+
+int find(int x) {
+    return fa[x] = fa[x] != x ? find(fa[x]) : fa[x];
+}
+
+int main() {
+    cin >> n >> m;
+    for (int i = 0; i < m; i++) {
+        cin >> g[i].u >> g[i].v >> g[i].w;
+    }
+    sort(g, g + m);
+    for (int i = 1; i <= n; i++) {
+        fa[i] = i;
+    }
+    for (int i = 0; i < m; i++) {
+        g[i].u = find(g[i].u);
+        g[i].v = find(g[i].v);
+        if (g[i].u != g[i].v) {
+            fa[g[i].u] = g[i].v;
+            res += g[i].w;
+            cnt++;
+        }
+    }
+    if (cnt < n - 1) {
+        cout << "impossible" << endl;
+    } else {
+        cout << res << endl;
+    }
+    return 0;
+}