*Trap Rain Water

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) 
    {
        int len = height.length;
        if(len<=2)return 0;
        int maxIndex = -1;
        int maxHgt = Integer.MIN_VALUE;
        for (int i=0;i<len;i++)
        {
            if(height[i]>maxHgt)
            {
                maxHgt = height[i];
                maxIndex = i;
            }
        }
        
        int leftMax = height[0];
        int rightMax = height[len-1];
        int water = 0;
        
        for (int i=1;i<maxIndex;i++)
        {
            if(height[i]<leftMax)
            {
                water += leftMax - height [i]; 
            }
            else
            {
                leftMax = height[i];
            }
            
        }
        
        for(int i=len-2;i>maxIndex;i--)
        {
            if(height[i]<rightMax)
            {
                water += rightMax - height [i]; 
            }
            else
            {
                rightMax = height[i];
            }
            
        }
        
        return water;
        
    }
}