#include<bits/stdc++.h>
using namespace std;

typedef long long ll;
#define readc(x) scanf("%c",&x)
#define read(x) scanf("%d",&x)
#define read2(x,y) scanf("%d%d",&x,&y)
#define read3(x,y,z) scanf("%d%d%d",&x,&y,&z)
#define print(x) printf("%d\n",x)
#define mst(a,b) memset(a,b,sizeof(a))
#define pb push_back
#define mp make_pair
const int inf = 0x3f3f3f3f;
const int maxn = 1e6 + 5;
int sum[maxn],mx[maxn];
int cnt = 0;
stack<int> s,q;
int main(){
  for(int i = 0 ;i < maxn; i++)
    mx[i] = -inf;
  int t;
  read(t);
  getchar();
  char c;
  while(t--){
    scanf("%c",&c);
    getchar();
    if(c=='I'){
      int x;
      read(x);
      getchar();
      s.push(x);
      cnt++;
      sum[cnt] = sum[cnt-1] + x;
      mx[cnt] = max(mx[cnt-1],sum[cnt]);
    }
    if(c=='D'){
      if(cnt){
        cnt--;
        s.pop();
      }
    }
    if(c=='L'){
      if(cnt){
        cnt--;
        int top = s.top();
        s.pop();
        q.push(top);
      }
    }
    if(c=='R'){
        if(!q.empty()){
          cnt ++;
          int top = q.top();
          q.pop();
          s.push(top);
          sum[cnt] = sum[cnt-1]+top;
          mx[cnt] = max(mx[cnt-1],sum[cnt]);
        }
    }
    if(c=='Q'){
      int x ;
      read(x);
      getchar();
      print(mx[x]);
    }
  }
}

看到了吧，大部分人都会这么做。但是，我不一样。ε=(′ο｀*)))唉，谁叫我是个智障天才呢。

#include<iostream>
#include<cstring>
using namespace std;
int stack[100011],a[100011];
int top,now,n,op;
char x;
int fun(){
    int max=-1234567890,ans=0;
    for(int i=0;i<op;i++){
        ans+=stack[i];
        if(ans>max){
            max=ans;
        }
    }
    return max;
}
int main(){
    cin>>n;
    for(int i=0;i<n;i++){
        cin>>x;
        if(x=='I'){
            cin>>stack[top++];
        }
        else if(x=='D'){
            top--;
        }
        else if(x=='T'){
            stack[top-1]-=10;
        }
        else if(x=='E'){
            top=top-3;
        }
        else{
            cin>>op;
            cout<<fun()<<endl;
        }
    }
}