40-Trapping Rain Water

#include <bits/stdc++.h> 
long getTrappedWater(long *arr, int n){
    // Write your code here.
    //Optimal code using two pointer approach
        long long left=0,right=n-1;
        long long res=0;
        long long maxLeft=0,maxRight=0;
        
        while(left<=right){
            if(arr[left] <= arr[right]){
                
                if(arr[left] >= maxLeft) maxLeft=arr[left];
                else res+=maxLeft-arr[left];
                
                left++;
            }
            else{
                if(arr[right] >= maxRight) maxRight=arr[right];
                else res+=maxRight-arr[right];
                
                right--;
            }
        }
        
        return res;
}