Create L13-2.cpp

L13-2.cpp

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+#include <bits/stdc++.h>
+using namespace std;
+
+typedef long long ll;
+typedef pair<int, int> pi;
+
+#define PUB push_back
+#define fi first
+#define se second
+
+const ll MOD = 1e9+7;
+
+int N, memo[3][100005];
+vector<int> adjL[100005];
+
+int DP(int prn, int pos, int stt){
+	// stt 	-> 0 : parentku putih, aku putih
+	//		-> 1 : kolam
+	//		-> 2 : parentku hitam, aku putih
+
+	int &ret = memo[stt][pos];
+	if(ret >= 0) return ret;
+
+	ret = 0;
+	if(stt == 1) ret = 1;
+	if(stt == 0) ret = 1e6;
+
+	for(int nxt:adjL[pos]){
+		if(nxt == prn) continue;
+
+		if(stt == 0){
+			int tmp = DP(pos, nxt, 1);
+
+			for(int nxt2:adjL[pos]){
+				if(nxt2 == prn || nxt2 == nxt) continue;
+				tmp += DP(pos, nxt2, 0);
+			}
+
+			ret = min(ret, tmp);
+		}else if(stt == 1){
+			ret += min(DP(pos, nxt, 1), DP(pos, nxt, 2));
+		}else{
+			ret += DP(pos, nxt, 0);
+		}
+	}
+
+	return ret;
+}
+
+int main(){
+	ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
+	memset(memo, -1, sizeof memo);
+
+	cin >> N;
+
+	for(int i=0;i<N-1;i++){
+		int u, v;
+		cin >> u >> v;
+		adjL[u].PUB(v);
+		adjL[v].PUB(u);
+	}
+
+	int ans = min(DP(1, 1, 0), DP(1, 1, 1));
+	cout << ans << endl;
+	return 0;
+}