Validate Stack Sequences

Given two integer arrays pushed and popped each with distinct values, return true if this could have been the result of a sequence of push and pop operations on an initially empty stack, or false otherwise.

Example 1:

Input: pushed = [1,2,3,4,5], popped = [4,5,3,2,1]
Output: true
Explanation: We might do the following sequence:
push(1), push(2), push(3), push(4),
pop() -> 4,
push(5),
pop() -> 5, pop() -> 3, pop() -> 2, pop() -> 1

Example 2:

Input: pushed = [1,2,3,4,5], popped = [4,3,5,1,2]
Output: false
Explanation: 1 cannot be popped before 2.

Approach

Java

import java.util.Stack;

public class ValidateStackSequence {
    public static void main(String[] args) {

        int pushed[] = { 1, 2, 3, 4, 5 }, popped[] = { 4, 5, 3, 2, 1 };

        System.out.println(validateStackSequences(pushed, popped));
    }

    public static boolean validateStackSequences(int[] pushed, int[] popped) {

        Stack<Integer> st = new Stack<Integer>();

        int j = 0;

        // iterate through the whole array
        for (int i = 0; i < pushed.length; i++) {

            // insert the current element into stack
            st.push(pushed[i]);

            // iterate till the size of stack is greater than 0 and
            // current element is the stack top element
            while (st.size() > 0) {
                if (popped[j] == st.peek()) {
                    st.pop();
                    j++;
                } else
                    break;
            }

        }

        // iterate through the remaining elements of the popped
        // array
        for (int i = j; i < popped.length; i++) {

            // if at any point top element is not
            // equal to the current element then
            // return false
            if (st.peek() != popped[i]) {
                return false;
            }
        }

        // at the end return true
        return true;
    }
}

C++

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

bool validateStackSequences(vector<int>& pushed, vector<int>& popped) {
        stack<int> st;
                int j=0;
        // iterate through the whole array
        for (int i = 0; i < pushed.size(); i++) {

            // insert the current element into stack
            st.push(pushed[i]);

            // iterate till the size of stack is greater than 0 and
            // current element is the stack top element
            while (st.size() > 0) {
                if (popped[j] == st.top()) {
                    st.pop();
                    j++;
                } else
                    break;
            }

        }

        // iterate through the remaining elements of the popped
        // array
        for (int i = j; i < popped.size(); i++) {

            // if at any point top element is not
            // equal to the current element then
            // return false
            if (st.top() != popped[i]) {
                return false;
            }
        }

        // at the end return true
        return true;
    }
int main()
{
    vector<int> pushed = { 1, 2, 3, 4, 5 }, 
             popped = { 4, 5, 3, 2, 1 };
    cout << validateStackSequences(pushed,popped);
    return 0;
}