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!
public class Solution { public int trap(int[] height) { if(height == null || height.length == 0) return 0; int res = 0; int left = 0; int right = height.length - 1; int lm = height[left]; int rm = height[right]; while (left < right) { if(height[left] < height[right]) { if(height[left] < lm) res += (lm - height[left]); else lm = height[left]; left++; } else { if(height[right] < rm) res += (rm - height[right]); else rm = height[right]; right--; } } return res; }}新闻热点
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