Codeforces 447C - DZY Loves Sequences

447C - DZY Loves Sequences

思路：dp

代码：

#include<bits/stdc++.h>
using namespace std;
#define ll long long
const int INF=0x3f3f3f3f;
const int N=1e5+;
int a[N];
int f[N],g[N];
int main()
{
    ios::sync_with_stdio(false);
    cin.tie();
    int n;
    cin>>n;
    f[]=;
    cin>>a[];
    for(int i=;i<=n;i++)
    {
        cin>>a[i];
        if(a[i]>a[i-])f[i]=f[i-]+;
        else f[i]=;
    }
    g[n]=;
    for(int i=n-;i>=;i--)
    {
        if(a[i]<a[i+])g[i]=g[i+]+;
        else g[i]=;
    }
    int ans=max(g[]+,f[n-]+);
    for(int i=;i<n;i++)
    ans=max(ans,max(f[i]+,g[i]+));
    for(int i=;i<n;i++)
    {
        if(a[i+]>a[i-]+)ans=max(ans,f[i-]++g[i+]);
    }
    cout<<ans<<endl;
    return ;
}