TrappingWater.java

package com.programs;

public class TrappingWater {
	public static int trappingWater(int [] height) {
		int leftMax[]=new int[height.length];
		leftMax[0]=height[0];
		for(int i=1;i<height.length;i++) {
			leftMax[i]=Math.max(height[i], leftMax[i-1]);
		}
		int rightMax[]=new int[height.length];
		rightMax[height.length-1]=height[height.length-1];
		for(int i=height.length-2;i>=0;i--) {
			rightMax[i]=Math.max(height[i], rightMax[i+1]);
		}
		
		int trappedWater=0;
		for(int i=0;i<height.length;i++) {
			int waterLevel=Math.min(leftMax[i], rightMax[i]);
			trappedWater+=waterLevel-height[i];
		}
		return trappedWater;
		
	}

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		int [] height= {4,2,0,6,3,2,5};
		System.out.println(trappingWater(height));

	}

}