BOJ 2533

2533.cpp

#include<iostream>
#include<algorithm>
#include<vector>
#include<cstdio>
using namespace std;

int dp[1000001][2];
bool visited[1000001];
vector<vector<int> >v;
int dfs(int cur, bool adp)
{
	int &ret = dp[cur][adp];
	if (ret != -1) return ret;
	visited[cur] = true;
	ret = adp ? 1 : 0;
	for (int there : v[cur])
	{
		if (!visited[there])
		{
			if(!adp) ret += dfs(there, true);
			else ret += min(dfs(there, true), dfs(there, false));
		}
	}
	visited[cur] = false;
	return ret;
}
int main()
{
	int n;

	scanf("%d", &n);
	v.resize(n + 1);
	for (int i = 0; i < n-1; i++)
	{
		int x, y;

		scanf("%d %d", &x, &y);
		v[x].push_back(y);
		v[y].push_back(x);
	}
	for (int i = 1; i <= n; i++) dp[i][0] = dp[i][1] = -1;
	cout << min(dfs(1, true), dfs(1, false));
}