public static void main(String args[]){
        int input[] = {0,1,0,2,1,0,1,3,2,1,2,1};
        TrappingWater tw = new TrappingWater();
        System.out.println(tw.trap(input));
    }
References
https://oj.leetcode.com/problems/trapping-rain-water/
https://leetcode.com/problems/trapping-rain-water/
src/com/interview/array/TrappingWater.java