hdu 5325 Crazy Bobo 乱搞+搜索

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

73 30 350 100 200 300 4001 22 33 44 55 66 7

 

Sample Output

5

 

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 // 1e6int 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("%d\n", maxn);    }    return 0;}