P1265 公路修建

R41298695

problem/P1265/P1265.cpp

@@ -0,0 +1,47 @@
+#include <bits/stdc++.h>
+
+using namespace std;
+
+struct point {
+    long long x, y;
+};
+
+int       n, m;
+bool      v[5005];
+long long d[5005];
+point     city[5005];
+
+void prim() {
+    memset(d, 0x3f, sizeof(d));
+    memset(v, 0x00, sizeof(v));
+    d[1] = 0;
+    for (int i = 1; i <= n - 1; i++) {
+        int x = 0;
+        for (int j = 1; j <= n; j++) {
+            if (!v[j] && (x == 0 || d[j] < d[x])) {
+                x = j;
+            }
+        }
+        v[x] = 1;
+        for (int y = 1; y <= n; y++) {
+            if (!v[y]) {
+                d[y] = min(d[y], (city[x].x - city[y].x) * (city[x].x - city[y].x) + (city[x].y - city[y].y) * (city[x].y - city[y].y));
+            }
+        }
+    }
+    return;
+}
+
+int main() {
+    cin >> n;
+    for (int i = 1; i <= n; i++) {
+        cin >> city[i].x >> city[i].y;
+    }
+    prim();
+    double ans = 0.00;
+    for (int i = 1; i <= n; i++) {
+        ans += sqrt((double)(d[i]));
+    }
+    cout << fixed << setprecision(2) << ans << endl;
+    return 0;
+}