1381.cpp

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

class CustomStack {
public:
    vector<int> st;
    vector<int> increments;
    int n;
    CustomStack(int maxSize) {
        n = maxSize;
    }
    
    void push(int x) {
        if(st.size() < n){
            st.push_back(x);
            increments.push_back(0);
        }
    }
    
    int pop() {
        if(st.size() == 0){
            return -1;
        } 
        int idx = st.size()-1;
        if(idx > 0){
            increments[idx-1] += increments[idx];
        }
        int val = st[idx] + increments[idx];
        st.pop_back();
        increments.pop_back();
        return val;
    }
    
    void increment(int k, int val) {
        int idx = min(k , (int) st.size())-1;
        if(idx >= 0 ){
            increments[idx] += val;
        }
    }
};

/**
 * Your CustomStack object will be instantiated and called as such:
 * CustomStack* obj = new CustomStack(maxSize);
 * obj->push(x);
 * int param_2 = obj->pop();
 * obj->increment(k,val);
 */
int main(){
    return 0;
}