剑指 Offer 31. 栈的压入、弹出序列

直接模拟就好了。

剑指 Offer 31. 栈的压入、弹出序列

class Solution {
    public boolean validateStackSequences(int[] pushed, int[] popped) {
        //泛型需要是对象类型所以不能用int
        Stack<Integer> stack = new Stack<>();
        int i = 0;
        for(int num : pushed){
            stack.push(num);
            //根据代码执行顺序，isEmpty()要写在前面
            while(!stack.isEmpty() && popped[i] == stack.peek()){
                stack.pop();
                i++;
            }
        }
       return stack.isEmpty();
    }
}