leetcode 456. 132 模式(java)

刚学完单调栈 

做题理解一下

感谢三叶姐呜呜呜

class Solution {
    public boolean find132pattern(int[] nums) {
        int n = nums.length;
        int k = Integer.MIN_VALUE;
        Deque<Integer> deque = new ArrayDeque<>();

        for(int i = n - 1; i >= 0; i --){
            if(nums[i] < k) return true;
            while(!deque.isEmpty() && deque.peekLast() < nums[i]){
                k = Math.max(k, deque.pollLast());
            }
            deque.addLast(nums[i]);
        }
        return false;
    }
}