Best Sightseeing Pair in C++

Suppose we have an array A of positive integers, now A[i] represents the value of the i-th sightseeing spot, and two sightseeing spots i and j have distance j - i. Now the score of a pair (i < j) of sightseeing spots is follows this formula (A[i] + A[j] + i - j): We have to find the maximum score of a pair of sightseeing spots. So if the input is like [8,1,5,2,6], then the output will be 11, as i = 0, j = 2, the value of A[0] + A[2] + 0 – 2 = 8 + 5 + 0 – 2 = 11.

To solve this, we will follow these steps −

• Set ret := 0, maxVal := 0, set n := size of A

• for i in range 0 to n – 1

  • ret := max of ret and (maxVal + A[i] – i)

  • maxVal := max of (A[i] + i) and maxVal

• return ret

Let us see the following implementation to get better understanding −

Example

 Live Demo

#include <bits/stdc++.h>
using namespace std;
class Solution {
   public:
   int maxScoreSightseeingPair(vector<int>& A) {
      int ret = 0;
      int maxVal = 0;
      int n = A.size();
      for(int i = 0; i < n; i++){
         ret = max(ret, maxVal + A[i] - i);
         maxVal = max(A[i] + i, maxVal);
      }
      return ret;
   }
};
main(){
   vector<int> v1 = {8, 1, 5, 2, 6};
   Solution ob;
   cout << (ob.maxScoreSightseeingPair(v1));
}

Input

[8,1,5,2,6]

Output

11

Arnab Chakraborty

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Updated on: 30-Apr-2020

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