Trapping Rain Water.cpp

//{ Driver Code Starts
#include <bits/stdc++.h>

using namespace std;


// } Driver Code Ends
class Solution {
  public:
    int maxWater(vector<int> &arr) {
        // code here
        int n = arr.size();
        if (n == 0) return 0;

        int left = 0, right = n - 1;
        int maxLeft = 0, maxRight = 0;
        int waterTrapped = 0;

        while (left <= right) {
            if (arr[left] <= arr[right]) {
                if (arr[left] >= maxLeft) {
                    maxLeft = arr[left];
                } else {
                    waterTrapped += maxLeft - arr[left];
                }
                left++;
            } else {
                if (arr[right] >= maxRight) {
                    maxRight = arr[right];
                } else {
                    waterTrapped += maxRight - arr[right];
                }
                right--;
            }
        }

        return waterTrapped;
    }
};

//{ Driver Code Starts.
int main() {
    int t;
    cin >> t;
    cin.ignore();
    while (t--) {
        vector<int> arr;
        string input;

        // Read first array
        getline(cin, input);
        stringstream ss(input);
        int number;
        while (ss >> number) {
            arr.push_back(number);
        }

        Solution ob;
        int res = ob.maxWater(arr);

        cout << res << endl << "~" << endl;
    }
    return 0;
}

// } Driver Code Ends