lec6_15.cpp

//{ Driver Code Starts
#include<bits/stdc++.h>
using namespace std;


// } Driver Code Ends
class Solution
{
    public:
    //Function to find the next greater element for each element of the array.
    vector<long long> nextLargerElement(vector<long long> arr, int n){
        // Your code here
        
        vector<long long>ans(n , -1);
        stack<int>st;
        
        for( int i = n-1; i>=0  ; i--)
        {
            
            while( !st.empty() && arr[st.top()]<arr[i])
            
           { 
               st.pop();
               
           }
            
            if(!st.empty())
            {
                ans[i] =  arr[st.top()];
                
            }
            
            st.push(i);
        };
        
        return ans;
    }
};

//{ Driver Code Starts.

int main()
{
    int t;
    cin>>t;
    while(t--)
    {
        
        int n;
        cin>>n;
        vector<long long> arr(n);
        for(int i=0;i<n;i++)
            cin>>arr[i];
        
        Solution obj;
        vector <long long> res = obj.nextLargerElement(arr, n);
        for (long long i : res) cout << i << " ";
        cout<<endl;
    }
	return 0;
}
// } Driver Code Ends