946. Validate Stack Sequences

https://leetcode.com/problems/validate-stack-sequences/

Python

from collections import deque


class Solution:
    def validateStackSequences(self, pushed: List[int], popped: List[int]) -> bool:
        remains = deque(popped)
        stack = []

        for num in pushed:
            stack.append(num)
            while stack and stack[-1] == remains[0]:
                stack.pop()
                remains.popleft()

        return not remains

Rust

impl Solution {
    pub fn validate_stack_sequences(pushed: Vec<i32>, popped: Vec<i32>) -> bool {
       let mut stack = Vec::new();
        let mut pop_index = 0;
        for num in pushed {
            stack.push(num);
            while let Some(&top) = stack.last() {
                if top == popped[pop_index] {
                    stack.pop();
                    pop_index += 1;
                } else {
                    break;
                }
            }
        }
        pop_index == popped.len()
    }
}

Go

func validateStackSequences(pushed []int, popped []int) bool {
    stack := []int{}
    popIndex := 0
    for _, num := range pushed {
        stack = append(stack, num)
        for len(stack) > 0 && stack[len(stack)-1] == popped[popIndex] {
            stack = stack[:len(stack)-1]
            popIndex++
        }
    }
    return popIndex == len(popped)
}