Trapping Rain Water

Posted cxchanpin

tags:

篇首语:本文由小常识网(cha138.com)小编为大家整理,主要介绍了Trapping Rain Water相关的知识,希望对你有一定的参考价值。

题目

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

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

技术分享

方法

对于每个A[i],trap water 为 min(left, right)- A[i];
    public int trap(int[] A) {
        if (A == null || A.length == 0 || A.length == 1 || A.length == 2) {
            return 0;
        }
        int len = A.length;
        int[] left = new int[len];
        int[] right = new int[len];
        int leftMax = 0;
        for (int i = 0; i < len; i++) {
        	left[i] = leftMax;
        	if (A[i] > leftMax) {
        		leftMax = A[i];
        	}
        }
        int rightMax = 0;
        for (int i = len; i > 0; i--) {
        	right[i - 1] = rightMax;
        	if (A[i - 1] > rightMax) {
        		rightMax = A[i - 1];
        	}
        }
        
        int sum = 0;
        for (int i = 0; i < len; i++) {
        	int temp = Math.min(left[i], right[i]) - A[i];
        	if (temp > 0) {
        		sum += temp;
        	}
        }
        return sum;
    }





以上是关于Trapping Rain Water的主要内容,如果未能解决你的问题,请参考以下文章

42. Trapping Rain Water *HARD*

[LeetCode] 42. Trapping Rain Water

LeetCode 42. Trapping Rain Water

[LeetCode] 407. Trapping Rain Water II

Trapping Rain Water 解答

Trapping Rain Water