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:
2 <= A.length <= 50000
1 <= A[i] <= 1000
解题思路
维护两个状态转移方程：
res = max(res, cur+a)cur = max(cur, a) - 1
cur表示曾经遇到过的最大得分，但是它每走一步都会衰减1，res当前到当前的最大得分。
实现代码
// Runtime: 4 ms, faster than 67.70% of Java online submissions for Best Sightseeing Pair.
// Memory Usage: 50.3 MB, less than 100.00% of Java online submissions for Best Sightseeing Pair.
class Solution {
public int maxScoreSightseeingPair(int[] A) {
int res = 0, cur = 0;
for (int a : A) {
res = Math.max(res, cur + a);
cur = Math.max(cur, a) - 1;
}
return res;
}
}
