面试题笔记

public class Solution {    public static void main(String[] args){        int[] nums =  {3,3,3};        System.out.println(trap(nums));
    }
    static int trap(int[] height){        int ans = 0;        int left = 0, right = height.length - 1;        int leftMax = 0, rightMax = 0;        while (left < right) {            leftMax = Math.max(leftMax, height[left]);            rightMax = Math.max(rightMax, height[right]);            if (height[left] < height[right]) {                //关键点1.1 计算这个格子能装多少水                ans += leftMax ;                ++left;            } else {//关键点2 反之，就移动右边界,这说明左边肯定能接住                //关键点2.1 计算这个格子能装多少水                ans += rightMax ;                --right;            }
        }        return ans;

    }


}