P1536 村村通

R43106178

problem/P1536/P1536.cpp

@@ -0,0 +1,33 @@
+#include <bits/stdc++.h>
+
+using namespace std;
+
+int n, m, x, y, ans, f[100005];
+
+int find(int x) {
+    if (f[x] == x) return x;
+    return f[x] = find(f[x]);
+}
+
+void unity(int x, int y) {
+    f[find(x)] = find(y);
+}
+
+int main() {
+    while (cin >> n, n) {
+        ans = 0;
+        cin >> m;
+        for (int i = 1; i <= n; i++) {
+            f[i] = i;
+        }
+        for (int i = 1; i <= m; i++) {
+            cin >> x >> y;
+            unity(x, y);
+        }
+        for (int i = 1; i <= n; i++) {
+            if (find(i) == i) ans++;
+        }
+        cout << --ans << endl;
+    }
+    return 0;
+}