new file: P2016.cpp

P2016.cpp

@@ -0,0 +1,29 @@
+#include<bits/stdc++.h>
+using namespace std;
+int n;
+vector<int> fri[1505];
+int dp[1505][2];
+void dfs(int now, int from) {
+    dp[now][1] = 1, dp[now][0] = 0;
+    for(int i:fri[now]) {
+        if(i == from) continue;
+        dfs(i, now);
+        dp[now][0] += dp[i][1];
+        dp[now][1] += min(dp[i][0], dp[i][1]);
+    }
+}
+int main() {
+    scanf("%d", &n);
+    for(int i = 0, k, now; i < n; ++i) {
+        scanf("%d%d", &now, &k);
+        while(k--) {
+            int r;
+            scanf("%d", &r);
+            fri[now].push_back(r);
+            fri[r].push_back(now);
+        }
+    }
+    dfs(0, -1);
+    printf("%d\n", min(dp[0][0], dp[0][1]));
+    return 0;
+}