剑指offer31.栈的压入、弹出序列。简单易懂0ms

class Solution {
    public boolean validateStackSequences(int[] pushed, int[] popped) {
        Deque<Integer> stack = new ArrayDeque();
        int j = 0;// j当作popped的指针，判断当前是否是弹出的数值
        for(int push : pushed){
            stack.push(push);
            // peek()是取出来并不删除,pop()是取出然后删除
            while(j < popped.length && !stack.isEmpty() && stack.peek() == popped[j]){
                stack.pop();
                j++;
            }
        }
        return j == popped.length;
    }
}