Leetcode 1021 Best Sightseeing Pair

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: [8,1,5,2,6]
Output: 11
Explanation: i = 0, j = 2, A[i] + A[j] + i - j = 8 + 5 + 0 - 2 = 11

 

Note:

1. 2 <= A.length <= 50000
2. 1 <= A[i] <= 1000

 

观察A[i]+A[j]+i-j，可以拆成A[i]+i,A[j]-j，所以维护一下这个A[i]+i和A[i]-i就可以O(n)写出，因为i

class Solution {
public:
    int maxScoreSightseeingPair(vector& num) {
        int len=num.size();
        int maxx=-0x3f3f3f3f;
        int ans=0;
        for(int i=0;i