#include<iostream>
#include<stack>
#define IO ios::sync_with_stdio(0);cin.tie(0);cout.tie(0)
#define int long long
using namespace std;
int n,h[50005],v[50005],s[50005],maxx=-1;
stack<int> st;
signed main(){
    IO;
    cin>>n;
    for(int i=1;i<=n;i++){
        cin>>h[i]>>v[i];
        //左边
        while(!st.empty()&&h[st.top()]<=h[i]) st.pop();
        if(!st.empty()) s[st.top()]+=v[i];
        st.push(i);
    }while(!st.empty()) st.pop();for(int i=n;i>=1;i--){
        //右边
        while(!st.empty()&&h[st.top()]<=h[i]) st.pop();
        if(!st.empty()) s[st.top()]+=v[i];
        st.push(i);
    }for(int i=1;i<=n;i++) maxx=max(maxx,s[i]);
    cout<<maxx;
    return 0;
}

此题有点让我无法形容

#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;
int const xn=50005;
int n,h[xn],v[xn],sta[xn],top,s[xn];
int rd()
{
  int ret=0,f=1; char ch=getchar();
  while(ch<'0'||ch>'9'){if(ch=='-')f=0; ch=getchar();}
  while(ch>='0'&&ch<='9')ret=(ret<<3)+(ret<<1)+ch-'0',ch=getchar();
  return f?ret:-ret;
}
int main()
{
  n=rd();
  for(int i=1;i<=n;i++)
    {
      h[i]=rd(),v[i]=rd();
      while(top&&h[sta[top]]<=h[i])top--;
      if(top)s[sta[top]]+=v[i];
      sta[++top]=i;
    }
  top=0;
  for(int i=n;i;i--)
    {
      while(top&&h[sta[top]]<=h[i])top--;
      if(top)s[sta[top]]+=v[i];
      sta[++top]=i;
    }
  int mx=0;
  for(int i=1;i<=n;i++)mx=max(mx,s[i]);
  printf("%d\n",mx);
  return 0;
}