UVA 10859 Placing Lampposts 树形dp（水

题目链接：点击打开链接

题意：

白书P70

思路：

简单题，每个点分放或不放。

import java.io.PrintWriter;import java.util.ArrayList;import java.util.Scanner;public class Main {int min(int a,int b){return a>b?b:a;}int max(int a,int b){return a>b?a:b;}static int N = 1005;static int M = 2005;ArrayList<Integer>[] G = new ArrayList[N];int n, m;boolean[] vis = new boolean[N];int[][] dp = new int[N][2];int dfs(int u){vis[u] = true;int ans = 0;dp[u][0] = 0; dp[u][1] = M;//0表示不放for(int i = 0; i < G[u].size(); i++){int v = G[u].get(i); if(vis[v])continue;dfs(v);dp[u][1] += min(dp[v][0]+1, dp[v][1]);dp[u][0] += dp[v][1]+1;}return min(dp[u][0], dp[u][1]);}void init(){n = cin.nextInt(); m = cin.nextInt();for(int i = 0; i < n; i++){vis[i] = false;G[i].clear();}for(int i = 1, u, v; i <= m; i++){u = cin.nextInt(); v = cin.nextInt();G[u].add(v); G[v].add(u);}}void work() {for(int i = 0; i < N; i++)G[i] = new ArrayList();int T; T = cin.nextInt();while(T-->0){init();int ans = 0;for(int i = 0; i < n; i++)if(vis[i] == false)ans += dfs(i);out.printf("%d %d %d", ans/M, m-ans%M, ans%M); out.println();}}Main() {cin = new Scanner(System.in);out = new PrintWriter(System.out);}public static void main(String[] args) {Main e = new Main();e.work();out.close();}public Scanner cin;public static PrintWriter out;}