New Exercise

Exercise/Homework8/Q3MiniTree.cpp

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+#include <iostream>
+#include <vector>
+#include <tuple>
+#include <algorithm>
+
+using namespace std;
+
+int find(int x, vector<int>& p) {
+    if(p[x] != x) p[x] = find(p[x], p);
+    return p[x];
+}
+
+int main() {
+    ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+    
+    int n, m;
+    cin >> n >> m;
+    int vir = n;//虚拟节点
+    n++;
+    vector<tuple<int, int, int>> edges;
+
+    vector<int> p(n);
+    for (int i = 0; i < n - 1; i++) {
+        cin >> p[i];
+        edges.push_back(make_tuple(vir, i, p[i]));
+    }
+
+    for(int i = 0; i < m; i++){
+        int a, b, w;
+        cin >> a >> b >> w;
+        edges.push_back(make_tuple(a, b, w));
+    }
+
+    auto cmp = [](const tuple<int, int, int>& a, const tuple<int, int, int>& b) {
+        return get<2>(a) < get<2>(b);
+    };
+    sort(edges.begin(), edges.end(), cmp);
+
+
+    for(int i = 0; i < n; i++) {
+        p[i] = i;
+    }
+    
+    
+    
+    int mins = 0;
+    int used = 0;
+    for(int i = 0; i < edges.size(); i++) {
+        int u = get<0>(edges[i]);
+        int v = get<1>(edges[i]);
+        int w = get<2>(edges[i]);
+        
+        int pu = find(u, p);
+        int pv = find(v, p);
+        if(pu != pv) {
+            p[pu] = pv;
+            mins += w;
+            used++;
+            if(used == n - 1) break; 
+        }
+    }
+
+    cout << mins << endl;
+
+    return 0;
+}