GFG PTOD | 12 Jan 2025 | Trapping Rain Water

int maxWater(vector<int> &arr) {
        // code here
        int i=0, j=arr.size()-1, lmax=0, rmax=0, ret=0;
        while(i<j) {
            if(arr[i] <= arr[j]) {
                if(lmax < arr[i]) lmax = arr[i];
                else ret += lmax - arr[i];
                i++;
            } else {
                if(rmax < arr[j]) rmax = arr[j];
                else ret += rmax - arr[j];
                j--;
            }
        }
        return ret;
    }