Validate Stack Sequences

LeetCode https://leetcode.cn/problems/validate-stack-sequences/

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

        Deque<Integer> stack = new ArrayDeque<Integer>();
        int n = pushed.length;
        for (int i = 0, j = 0; i < n; i++) {
            stack.push(pushed[i]);
            while (!stack.isEmpty() && stack.peek() == popped[j]) {
                stack.pop();
                j++;
            }
        }
        return stack.isEmpty();
    }
}

Complexity

• Time = O(n)
• Space = O(n)

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