RainWaterProblem

class RainWaterProblem {
    public static int findWater(int[] arr) {//arr length take out ArraySize
        int arr_size = arr.length;//we created new array of same size
        //first array of left max height include itself
        int left[] = new int[arr_size];//first array of right max height include itself
        int right[] = new int[arr_size];

        int water = 0; //Global varable store(OR)Initialize result
        
        left[0] = arr[0];//precompute left array//we are fill left side array
        for (int i = 1; i < arr_size; i++)
            left[i] = Math.max(left[i - 1], arr[i]);
        System.out.println("Left->");
        for (int i = 0; i < arr_size; i++)//print left
            System.out.print(left[i] + ",");
        System.out.println("");

        System.out.println("Right->");//print right array
        right[arr_size - 1] = arr[arr_size - 1];//precompute right array
        for (int i = arr_size - 2; i >= 0; i--)
            right[i] = Math.max(right[i + 1], arr[i]);
        for (int i = 0; i < arr_size; i++)//print Right
            System.out.print(right[i] + ",");
        System.out.println("");

        System.out.println("Water->");
        for (int i = 0; i < arr_size; i++) {
            water+= Math.min(left[i], right[i]) - arr[i];//calcu water  with min of left&right build - buildHeight
        }
            return water;
        }
        public static void main(String[]args){
            System.out.print("Building Height->\n");
            int arr[] = new int[]{0, 1, 0, 2, 1, 0, 1, 3, 2, 1, 2, 1};
            for (int i = 0; i < arr.length; i++)
                System.out.print(arr[i] + ", ");
            System.out.println(" ");
            int ans = findWater(arr);
            System.out.println("Total water:"+ ans);
        }
    }