Rocky Valley 1352 no boss's prom.

Rocky Valley 1352 no boss's prom.

Address: http://www.luogu.org/problem/show?pid=1352

Title Description

A university has N staff, numbered 1~n. They have a subordinate relationship, which means that their relationship is like a tree rooted in the headmaster, and the parent node is the direct boss of the child node. There's an anniversary party, and every invitation to an employee adds a certain amount of happiness to the RI, but if an employee's boss comes to the ball, the clerk will not come to the party anyway. So, please do your programming, invite the staff can make the happiness index biggest, seek the biggest happiness index.

Input/output format

Input format:

The first line is an integer n. (1<=n<=6000)
Next n lines, line i+1 represents the happiness index RI for staff i. ( -128<=ri<=127)
Next N-1 line, enter a pair of integer l, K for each line. Indicates that K is the direct boss of L.
Last line input 0 0

Output format:

Output the maximum happiness index.

Input/Output sample

Input Sample # #:

7

1

1

1

1

1

1

1

1 3

2 3

6 4

7 4

4 5

3 5

0 0

Sample # # of output:

5

Ideas

DP on Classic tree.

Set D[I][J] Indicates the maximum happiness value when the subtree state is s with the root of I, and s==0 indicates that there is no s==1 present. Then there is the transfer equation:

d[i][1]=sum{d[chi][0]}

D[I][0]=SUM{MAX{D[CHI][0],D[CHI][1]}}

It is important to note that when s==0, the subtree status is not necessarily 1.

Code

1#include <cstdio>2#include <iostream>3#include <cstring>4#include <vector>5 using namespacestd;6 7 Const intMAXN =6000+Ten;8 intr[maxn],d[maxn][2],CNT[MAXN];9vector<int>G[MAXN];Ten intN; One  A voiddpintu) { -     if(d[u][0])return ; -      the      for(intI=0; I<g[u].size (); i++) { -         intv=G[u][i]; - DP (v); -d[u][1] + = d[v][0]; +d[u][0] + = max (d[v][0],d[v][1]);//Max -     } +d[u][1] +=R[u]; A } at  - intMain () { -scanf"%d",&n); -      for(intI=1; i<=n;i++) scanf ("%d",&r[i]); -     intu,v; -      while(SCANF ("%d%d", &u,&v) && u &&v) inG[v].push_back (u), cnt[u]++; -     intRoot; to      for(intI=1; i<=n;i++)if(!Cnt[i]) { +root=i; Break; -     } the DP (root); *printf"%d", Max (d[root][1],d[root][0])); $     return 0;Panax Notoginseng}

Rocky Valley 1352 no boss's prom.