【CF1029B】Creating the Contest（贪心）

题意：

n<=2e5

思路：可以证明答案一定是极长的一段中取最大值

#include<cstdio>
#include<cstring>
#include<string>
#include<cmath>
#include<iostream>
#include<algorithm>
#include<map>
#include<set>
#include<queue>
#include<vector>
using namespace std;
typedef long long ll;
typedef unsigned int uint;
typedef unsigned long long ull;
typedef pair<int,int> PII;
typedef vector<int> VI;
#define fi first
#define se second 
#define MP make_pair
#define N   5100000
#define MOD 1e9+7 
#define eps 1e-8 
#define pi acos(-1)

int a[210000],dp[210000],ans,t,w;

            

int read()
{ 
   int v=0,f=1;
   char c=getchar();
   while(c<48||57<c) {if(c=='-') f=-1; c=getchar();}
   while(48<=c&&c<=57) v=(v<<3)+v+v+c-48,c=getchar();
   return v*f;
}

void swap(int &x,int &y)
{
    int t=x;x=y;y=t;
}


        
int main()
{
//    freopen("1.in","r",stdin);
//    freopen("1.out","w",stdout);
    int n;
    scanf("%d",&n);
    for(int i=1;i<=n;i++) a[i]=read();

    ans=1;
    w=1;
    t=0;
    dp[1]=1;
    for(int i=2;i<=n;i++) 
    {
        dp[i]=1;
        while(w+1<=n&&a[w]*2<a[i]) w++;
        while(w+1<i&&w+1<=n&&a[w+1]*2>=a[i]) w++;
        if(w<i) dp[i]=max(dp[i],dp[w]+1);
        ans=max(ans,dp[i]);
        //printf("%d %d %d
",i,w,dp[i]);
    }
    printf("%d",ans); 
    return 0;
}