946. Validate Stack Sequences

/**
 * Time Complexity: O(N)
 *
 * Space Complexity: O(N)
 *
 * N = length of the pushed or popped array.
 */
class Solution {
    public boolean validateStackSequences(int[] pushed, int[] popped) throws IllegalArgumentException {
        if (pushed == null || popped == null) {
            throw new IllegalArgumentException("Input array is null");
        }
        if (pushed.length != popped.length) {
            return false;
        }

        Stack<Integer> stack = new Stack();
        int i = 0;
        for (int p : pushed) {
            stack.push(p);
            while (!stack.isEmpty() && stack.peek() == popped[i]) {
                stack.pop();
                i++;
            }
        }

        return stack.isEmpty();
    }
}