题解 | #单调栈#

import java.util.*;


public class Solution {
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     *
     *
     * @param nums int一维数组
     * @return int二维数组
     */
    public int[][] foundMonotoneStack (int[] nums) {
        int[][] res = new int[nums.length][2];
        res[0][0] = -1;
        res[nums.length - 1][1] = -1;

        for (int i = 1; i < nums.length; i++) {
            int j = i - 1;
            while (j != -1 && nums[j] >= nums[i]) {
                j = res[j][0];
            }
            res[i][0] = j;
        }

        for (int i = nums.length - 2; i >= 0; i--) {
            int j = i + 1;
            while (j != -1 && nums[j] >= nums[i]) {
                j = res[j][1];
            }
            res[i][1] = j;
        }

        return res;
    }
}