luogu1901 发射站

#include<iostream>
#include<cstdlib>
#include<algorithm>
#include<cstdio>
#include<cmath>
#include<cstring>
#define ll long long
using namespace std;
const int maxn=1000000+50;
int st[maxn],top;
int n,a[maxn],v[maxn];
int ans[maxn];
int main()
{
    scanf("%d",&n);
    for(int i=1;i<=n;i++)scanf("%d%d",&a[i],&v[i]);
    for(int i=1;i<=n;i++)
    {
        while(top>0 && a[st[top]]<=a[i])top--;
        ans[st[top]]+=v[i];
        st[++top]=i;
    }
    top=0;
    int Ans=-1;
    for(int i=n;i>=1;i--)
    {
        while(top>0 && a[st[top]]<=a[i])top--;
        ans[st[top]]+=v[i];
        st[++top]=i;
    }
    for(int i=n;i>=1;i--)Ans=max(Ans,ans[i]);
    cout<<Ans;
}