您的位置：首页 > 其它

CodeForces - 633D Fibonacci-ish (map&暴力)

2016-03-12 16:07 387 查看
CodeForces
- 633D

Fibonacci-ish

Time Limit: 3000MS Memory Limit: 524288KB 64bit IO Format: %I64d & %I64u
Submit Status

Description

Yash has recently learnt about the Fibonacci sequence and is very excited about it. He calls a sequence Fibonacci-ish if

the sequence consists of at least two elements
f0 and f1 are arbitrary
fn + 2 = fn + 1 + fn for all n ≥ 0.
You are given some sequence of integers a1, a2, ..., an.
Your task is rearrange elements of this sequence in such a way that its longest possible prefix is Fibonacci-ish sequence.

Input

The first line of the input contains a single integer n (2 ≤ n ≤ 1000) — the length of the sequence ai.

The second line contains n integers a1, a2, ..., an (|ai| ≤ 109).

Output

Print the length of the longest possible Fibonacci-ish prefix of the given sequence after rearrangement.

Sample Input

Input
3
1 2 -1


Output
3


Input
5
28 35 7 14 21


Output
4


Hint

In the first sample, if we rearrange elements of the sequence as  - 1, 2, 1,
the whole sequence ai would be Fibonacci-ish.

In the second sample, the optimal way to rearrange elements is 

, 

, 

, 

, 28.

Source

Manthan, Codefest 16

//上次就遇见一个题，考试完听大神说是用map做的，这次又是一个map,看来是时候学一下map了。

这个是看大神的代码写的，还在理解中。。。

#include<stdio.h>
#include<string.h>
#include<algorithm>
#include<iostream>
#include<map>
#define INF 0x3f3f3f3f
#define ull unsigned long long
#define IN __int64#define ll long long
using namespace std;
int a[1010];
map<int,int>fp;
int dfs(int a,int b)
{
int ans=0;
if(fp[a+b])
{
fp[a+b]--;
ans=dfs(b,a+b)+1;
fp[a+b]++;
}
return ans;
}
int main()
{
int n;
while(scanf("%d",&n)!=EOF)
{
memset(a,0,sizeof(a));
fp.clear();
for(int i=0;i<n;i++)
{
scanf("%d",&a[i]);
fp[a[i]]++;
}
sort(a,a+n);
int ans=0;
int m=unique(a,a+n)-a;
for(int i=0;i<m;i++)
{
for(int j=0;j<m;j++)
{
if(i==j&&fp[a[i]]==1)
continue;
fp[a[i]]--;fp[a[j]]--;
ans=max(ans,dfs(a[i],a[j])+2);
fp[a[i]]++;fp[a[j]]++;
}
}
printf("%d\n",ans);
}
return 0;
}


内容来自用户分享和网络整理，不保证内容的准确性，如有侵权内容，可联系管理员处理 点击这里给我发消息
标签： 
相关文章推荐
新的分享
章节导航