[Leetcode] Trapping Rain Water

Given n non-negative integers representing an elevation map where the width of each bar are 1, compute how much WA ter It is the able to trap after raining.

For example,
Given [0,1,0,2,1,0,1,3,2,1,2,1] , return 6 .

The above elevation map is represented by array [0,1,0,2,1,0,1,3,2,1,2,1]. In this case, 6 units of the Rain Water (blue section) is being trapped. Thanks Marcos for contributing this image!

Reference: Dai Fangqin ([email protected]) Https://github.com/soulmachine/leetcode

public class Solution {public    int trap (int[] A) {        int sum = 0;    int Maxleft [] = new Int[a.length];        int Maxright [] = new int [a.length];        for (int i=1;i<a.length;i++) {        Maxleft[i] = Math.max (Maxleft[i-1], a[i-1]);        Maxright[a.length-1-i] = Math.max (Maxright[a.length-i], a[a.length-i]);        }        for (int i=0;i<a.length;i++) {        int height = math.min (maxleft[i],maxright[i]);        if (Height>=a[i]) {        sum + = Height-a[i];}        }        return sum;    }}

[Leetcode] Trapping Rain Water