Leader in an array.cpp

//  Leaders in an array
// Easy
// 0/40
// Average time to solve is 15m
// Contributed by
// Asked in companies
// Problem statement
// Given a sequence of numbers. Find all leaders in sequence. An element is a leader if it is strictly greater than all the elements on its right side.

// Note:
// 1. Rightmost element is always a leader.

// 2. The order of elements in the return sequence must be the same as the given sequence
// Example:
// The given sequence is 13, 14, 3, 8, 2 .

// 13 Not a leader because on the right side 14 is greater than 13.

// 14 lt is a leader because no one greater element in the right side.

// 3 Not a leader because on the right side 8 are greater than 3.

// 8 It is a leader because no one greater element on the right side.

// 2 It is a leader because it is the rightmost element in a sequence.

// Hence there are 3 leaders in the above sequence which are 14, 8, 2.
// Detailed explanation ( Input/output format, Notes, Images )
// Constraints:
// 1 <= T <= 50
// 1 <= N <= 10^4
// -10^9 <= ELEMENTS[i] <= 10^9

// Where ‘ELEMENTS[i]’ denotes an element at position ‘i’ in the sequence.

// Time limit: 1 sec
// Sample Input 1:
// 2
// 6
// 6 7 4 2 5 3
// 4
// 11 10 9 8
// Sample Output 1:
// 7 5 3
// 11 10 9 8
// Explanation of Sample Output 1:
// In test case 1,

// 6 Not a leader because on the right side 7 is greater than 6.

// 7 lt is a leader because no one greater element in the right side.

// 4 Not a leader because on the right side 5 are greater than 4.

// 2 Not a leader because on the right side 5, 3 are greater than 2.

// 5 lt is a leader because no one greater element in the right side.

// 3 It is a leader because it is a rightmost element in a sequence.

// Hence there are 3 leaders in sequence 7, 5, 3. 

// In test case 2,

// Given sequence is in descending order, so all elements are leaders
// Sample Input 2:
// 2
// 6
// 5 10 11 12 -1 -2
// 4
// 10 -11 -3 -2
// Sample Output 2:
// 12 -1 -2
// 10 -2
// Explanation of Sample Output 2:
// In test case 1,

// 5 Not a leader because on the right side 10 is greater than 5.

// 10 Not a leader because on the right side 11 is greater than 10.

// 11 Not a leader because on the right side 12 are greater than 11.

// 12 lt is a leader because no one greater element in the right side.

// -1 lt is a leader because no one greater element in the right side.

// -2 It is a leader because it is a rightmost element in a sequence.

// Hence there are 3 leaders in sequence 12, -1, -2. 

// In test case 2,

// 10 lt is a leader because no one greater element in the right side.

// -11 Not a leader because on the right side -3 are greater than -11.

// -3 Not a leader because on the right side -2 are greater than -3.

// -2 It is a leader because it is a rightmost element in a sequence.

// Hence there are 2 leaders in sequence 10, -2. 

#include <bits/stdc++.h> 
vector<int> findLeaders(vector<int> &elements, int n) {
    // Write your code here.
    vector<int>res;
    int maxE=INT_MIN;
    for(int i=n-1;i>=0;i--){
        if(elements[i]>maxE){
            maxE=elements[i];
            res.push_back(elements[i]);
        }
    } 
    reverse(res.begin(),res.end());
    return res;
}