Find minimum cost to buy all books in C++

Suppose we have an array of n elements. These are the ratings of them. Find the minimum cost to buy all books, with the following condition −

Cost of each book would be at-least 1 dollar
A book has higher cost than an adjacent (left or right) if rating is more than the adjacent.

So for example, if the rating array is like [1, 3, 4, 3, 7, 1], Then the output is 10, As 1 + 2 + 3 + 1 + 2 + 1 = 10

To solve this, we have to make two arrays called LtoR, and RtoL, and fill them with 1, now follow these steps −

Traverse left to right, then fill LtoR, and update it by seeing previous rating of the given array. We are not caring about the next rating of given array
Traverse right to left, then fill RtoL, and update it by seeing previous rating of the given array. We are not caring about the next rating of given array
For maximum value of ith position in both array LtoR and RtoL, then add it to the result.

Example

Live Demo

#include<iostream>
using namespace std;
int getMinCost(int ratings[], int n) {
   int res = 0;
   int LtoR[n];
   int RtoL[n];
   for(int i = 0; i<n; i++){
      LtoR[i] = RtoL[i] = 1;
   }
   for (int i = 1; i < n; i++)
   if (ratings[i] > ratings[i - 1])
      LtoR[i] = LtoR[i - 1] + 1;
   for (int i = n - 2; i >= 0; i--)
      if (ratings[i] > ratings[i + 1])
         RtoL[i] = RtoL[i + 1] + 1;
   for (int i = 0; i < n; i++)
      res += max(LtoR[i], RtoL[i]);
   return res;
}
int main() {
   int ratings[] = { 1, 6, 8, 3, 4, 1, 5, 7 };
   int n = sizeof(ratings) / sizeof(ratings[0]);
   cout << "Minimum cost is: " << getMinCost(ratings, n);
}