Mostwater.java

import java.util.ArrayList;
public class Mostwater {
    // public static int mostWater(ArrayList <Integer> arr){
    //     int max = Integer.MIN_VALUE;
    //     //brute force
    //     for(int i = 0; i<arr.size()-1; i++){
    //         for(int j = i+1 ;j <arr.size(); j++){
    //             int width = j-i;
    //             int height = Math.min(arr.get(i), arr.get(j));
    //             if(max < width * height){
    //                 max = width * height;
    //             }
    //         }
    //     }
    //     return max;
    // }

    //optimized
    public static int storeWater(ArrayList <Integer> list){
        int maxWater = Integer.MIN_VALUE;
        int lp = 0;
        int rp = list.size()-1;

        while(lp < rp){
            int ht = Math.min(list.get(lp), list.get(rp));
            int wd = rp - lp;
            int currWater = ht * wd;
            maxWater = Math.max(maxWater, currWater);

            if(list.get(lp) < list.get(rp)){
                lp++;
            }else{
                rp--;
            }
        }

        return maxWater;
    }
    public static void main(String args[]){
        int arr[] = {1,8,6,2,5,4,8,3,7};
        // System.out.println(mostWater(arr));

        ArrayList <Integer> height = new ArrayList<>();
        height.add(1);
        height.add(8);
        height.add(6);
        height.add(2);
        height.add(5);
        height.add(4);
        height.add(8);
        height.add(3);
        height.add(7);
        System.out.println(storeWater(height));
    }
}