LeetCode------42. Trapping Rain Water(捕获雨水量)

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!

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理解：补货雨水量（蓝色方块面积）

思路：从两边往中间搜索

public class Solution {
    public int trap(int[] height) {
        // for(int i=0;i<height.length()-2;i++){
            
        // }
        
        int secHight = 0;
		int left = 0;
		int right = height.length-1;
		int area = 0;
		while (left < right){
			if (height[left] <height[right]){
				secHight = Math.max(height[left], secHight);
				area += secHight-height[left];//计算当前格的能装雨水的容量
				left++;
			} else {
				secHight = Math.max(height[right], secHight);
				area += secHight-height[right];
				right--;
			}
		}
		return area;
    }
}