Best sightseeing pair

Time: O(N); Space: O(1); medium

Given an array A of positive integers, A[i] represents the value of the i-th sightseeing spot, and two sightseeing spots i and j have distance j - i between them.

The score of a pair (i < j) of sightseeing spots is (A[i] + A[j] + i - j): the sum of the values of the sightseeing spots, minus the distance between them.

Return the maximum score of a pair of sightseeing spots.

Example 1:

Input: A = [8, 1, 5, 2, 6]

Output: 11

Explanation:

i = 0, j = 2, A[i] + A[j] + i - j = 8 + 5 + 0 - 2 = 11

Notes:

• 2 <= len(A) <= 50000

• 1 <= A[i] <= 1000

class Solution1(object):
    def maxScoreSightseeingPair(self, A):
        """
        :type A: List[int]
        :rtype: int
        """
        result, curr = 0, 0
        for x in A:
            result = max(result, curr + x)
            curr = max(curr, x) - 1
        return result

s = Solution1()
A = [8, 1, 5, 2, 6]
assert s.maxScoreSightseeingPair(A) == 11

See also:

https://leetcode.com/problems/best-sightseeing-pair