LeetCode 42 Trapping Rain Water（积水体积）

package leetcode_50;


/***
 * 
 * @author pengfei_zheng
 * 求积水的体积
 */
public class Solution42 {
    public static int trap(int[] height) {
        if (height.length <= 2) return 0;
        int max = -1;
        int maxIndex = 0;
        for (int i = 0; i < height.length; i++) {
            if (height[i] > max) {
                max = height[i];
                maxIndex = i;
            }
        }
        
        int leftMax = height[0];
        int water = 0;
        for (int i = 1; i < maxIndex; i++) {
            if (height[i] > leftMax) {
                leftMax = height[i];
            } else {
                water += leftMax - height[i];
            }
        }
        
        int rightMax = height[height.length - 1];
        for (int i= height.length - 2; i > maxIndex; i--) {
            if (height[i] > rightMax) {
                rightMax = height[i];
            } else {
                water += rightMax - height[i];
            }
        }
        
        return water;
    }
    public static void main(String[]args){
//        int []height={0,1,0,2,1,0,1,3,2,1,2,1};
        int []height={10,0,11,0,10};
        System.out.println(trap(height));
    }
}