hdu 5325 Crazy Bobo 乱搞+搜索 Crazy Bobo

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我是靠谱客的博主苗条柠檬，最近开发中收集的这篇文章主要介绍hdu 5325 Crazy Bobo 乱搞+搜索 Crazy Bobo，觉得挺不错的，现在分享给大家，希望可以做个参考。

概述

Crazy Bobo

Time Limit: 6000/3000 MS (Java/Others) Memory Limit: 131072/65536 K (Java/Others)
Total Submission(s): 218 Accepted Submission(s): 60

Problem Description

Bobo has a tree,whose vertices are conveniently labeled by 1,2,...,n.Each node has a weight

wi . All the weights are distrinct.
A set with m nodes

v1,v2,...,vm is a Bobo Set if:
- The subgraph of his tree induced by this set is connected.
- After we sort these nodes in set by their weights in ascending order,we get

u1,u2,...,um ,(that is,

wui<wui+1 for i from 1 to m-1).For any node

x in the path from

ui to

ui+1 (excluding

ui and

ui+1 ),should satisfy

wx<wui .
Your task is to find the maximum size of Bobo Set in a given tree.

Input

The input consists of several tests. For each tests:
The first line contains a integer n (

1≤n≤500000 ). Then following a line contains n integers

w1,w2,...,wn (

1≤wi≤109 ,all the

wi is distrinct).Each of the following n-1 lines contain 2 integers

ai and

bi ,denoting an edge between vertices

ai and

bi (

1≤ai,bi≤n ).
The sum of n is not bigger than 800000.

Output

For each test output one line contains a integer,denoting the maximum size of Bobo Set.

Sample Input

  
  
   
   7
3 30 350 100 200 300 400
1 2
2 3
3 4
4 5
5 6
6 7

Sample Output

题目链接：http://acm.hdu.edu.cn/showproblem.php?pid=5325

解题思路：反正我是智商余额不足。。。

AC代码：顺着题解思路DFS了一下= =

#pragma comment(linker, "/STACK:1024000000,1024000000")
#include <iostream>
#include <cstdio>
#include <cstring>
#include <string>
#include <cmath>
#include <algorithm>
#include <vector>
#include <queue>
#include <set>
#include <map>
#include <stack>
#include <limits.h>
using namespace std;
typedef long long LL;
#define y1 y234
#define MAXN 500010 // 1e6
int n;
int a[MAXN];
vector<int> edge[MAXN];
int ans[MAXN];
void DFS(int u) {
    ans[u] = 1;
    int len = edge[u].size();
    for(int i = 0; i < len; i++) {
        int v = edge[u][i];
        if(!ans[v]) DFS(v);
        ans[u] += ans[v];
    }
}
int main() {
    while(~scanf("%d", &n)) {
        memset(ans, 0, sizeof ans);
        for(int i = 1; i <= n; i++) {
            scanf("%d", &a[i]);
            edge[i].clear();
        }
        int u, v;
        for(int i = 1; i < n; i++) {
            scanf("%d%d", &u, &v);
            if(a[u] < a[v]) edge[u].push_back(v);
            else if(a[v] < a[u]) edge[v].push_back(u);
        }
        for(int i = 1; i <= n; i++) {
            if(ans[i]) continue;
            DFS(i);
        }
        int maxn = -1;
        for(int i = 1; i <= n; i++) {
            maxn = max(ans[i], maxn);
        }
        printf("%dn", maxn);
    }
    return 0;
}