BZOJ2369【Tree DP】

/* I will wait for you */

#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <ctime>
#include <algorithm>
#include <iostream>
#include <fstream>
#include <vector>
#include <queue>
#include <deque>
#include <set>
#include <map>
#include <string>
#define make make_pair
#define fi first
#define se second

using namespace std;

typedef long long ll;
typedef unsigned long long ull;
typedef pair<int, int> pii;

const int maxn = 100010;
const int maxm = 1010;
const int maxs = 26;
const int inf = 0x3f3f3f3f;
const int P = 1000000007;
const double error = 1e-9;

inline int read()
{
	int x = 0, f = 1;
	char ch = getchar();
	while (ch < '0' || ch > '9')
		  f = (ch == '-' ? -1 : 1), ch = getchar();
	while (ch >= '0' && ch <= '9')
	 	  x = x * 10 + ch - '0', ch = getchar();
	return x * f;
}

struct edge 
{
	int v, next;
} e[maxn];

int n, cnt, f[maxn][20], head[maxn];

void insert(int u, int v) 
{
	e[cnt] = (edge) {v, head[u]};
	head[u] = cnt++;
	e[cnt] = (edge) {u, head[v]};
	head[v] = cnt++;
}

void dfs(int u, int p)
{
	for (int i = 1; i <= 10; i++)
		f[u][i] = i;
	
	for (int i = head[u]; i != -1; i = e[i].next) {
		int v = e[i].v;
		
		if (v != p) {
			dfs(v, u);
			for (int j = 1; j <= 10; j++) {
				int val = inf;
				for (int k = 1; k <= 10; k++)
					if (j != k)
						val = min(val, f[v][k]);
				f[u][j] += val;
			}
		}
	}
} 

int main()
{
	n = read();
	
	memset(head, -1, sizeof head);
	
	for (int i = 1; i < n; i++) {
		int u = read(), v = read();
		insert(u, v);
	}

	dfs(1, 0);
	
	int ans = inf;
	
	for (int i = 1; i <= 10; i++)
		ans = min(ans, f[1][i]);
	printf("%d
", ans);
	
	return 0;
}