LeetCode 0042 - Trapping Rain Water

Reck Zhang

发布于 2021-08-11 10:34:57

2280

发布于 2021-08-11 10:34:57

文章被收录于专栏：Reck Zhang

Trapping Rain Water

Desicription

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.

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 rain water (blue section) are being trapped. Thanks Marcos for contributing this image!

Solution

class Solution {
public:
    int trap(vector<int>& height) {
        if(!height.size())
            return 0;
        int left = 0;
        int right = height.size()-1;
        int left_max = height[left];
        int right_max = height[right];
        int res = 0;
        while(left <= right){
            if(height[left] <= height[right]){
                if(height[left] > left_max)
                    left_max = height[left];
                else
                    res += left_max - height[left];
                left++;
            }
            else{
                if(height[right] > right_max)
                    right_max = height[right];
                else
                    res += right_max - height[right];
                right--;
            }
        }
        return res;
    }
};

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原始发表：2017-11-11，如有侵权请联系 cloudcommunity@tencent.com 删除

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