CodeForces 447C###C. DZY Loves Sequences

题目传送门http://codeforces.com/problemset/problem/447/C

Description

DZY has a sequence a, consisting of n integers.

We'll call a sequence a_i, a_i + 1, ..., a_j(1 ≤ i ≤ j ≤ n) a subsegment of the sequence a. The value (j - i + 1) denotes the length of the subsegment.

Your task is to find the longest subsegment of a, such that it is possible to change at most one number (change one number to any integer you want) from the subsegment to make the subsegment strictly increasing.

You only need to output the length of the subsegment you find.

Input

The first line contains integer n (1 ≤ n ≤ 10⁵). The next line contains n integers a₁, a₂, ..., a_n (1 ≤ a_i ≤ 10⁹).

Output

In a single line print the answer to the problem — the maximum length of the required subsegment.

Sample Input

Input

67 2 3 1 5 6

Output

5

Hint

You can choose subsegment a₂, a₃, a₄, a₅, a₆ and change its 3rd element (that is a₄) to 4.

题意中的子串指连续子串,数字可以变成任意整数,可以不在1<a<1e9范围内,题意理解就好办了

#include<iostream>#include<cstdio>#include<cstring>#include<string>#include<algorithm>#include<map>#include<queue>#include<climits>#include<list>#include<stack>#include<cmath>#define ll long long#define MAX 1e9#define mem(a)  memset(a,0,sizeof(a))using  namespace std;int arr[110000];int bac[110000];// 可向前延伸的长度int forth[110000];//可向后延伸的长度 前后容易混淆int main(){    int n;    while(scanf("%d",&n)!=EOF)    {        mem(arr);        mem(bac);        mem(forth);        int i;        for(i=0;i<n;++i)        {            scanf("%d",&arr[i]);        }        bac[0]=1;        for(i=1;i<n;++i)        {            if(arr[i]>arr[i-1])            {                bac[i]=bac[i-1]+1;            }            else            {                bac[i]=1;            }        }        forth[n-1]=1;        for(i=n-2;i>=0;--i)        {            if(arr[i]<arr[i+1])            {                forth[i]=forth[i+1]+1;            }            else            {                forth[i]=1;            }        }        int ans=1;        for(i=1;i<n;++i)        {//            if(arr[i]>1&&forth[i]+1>ans)//change one number to any integer you want            if(arr[i]>1&&forth[i]+1>ans)            {                ans=forth[i]+1;            }        }        for(i=n-2;i>=0;--i)        {//            if(bac[i]<MAX&&bac[i]+1>ans)//change one number to any integer you want            if(bac[i]<MAX&&bac[i]+1>ans)            {                ans=bac[i]+1;            }        }        for(i=1;i<n-1;++i)        {            if(arr[i+1]-arr[i-1]>1)            {                ans=max(ans,bac[i-1]+forth[i+1]+1);            }        }        printf("%d\n",ans);    }}