【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[],dp[],ans,t,w;

 int read()
 {
    int v=,f=;
    char c=getchar();
    while(c<||<c) {if(c=='-') f=-; c=getchar();}
    while(<=c&&c<=) v=(v<<)+v+v+c-,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=;i<=n;i++) a[i]=read();

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