LeetCode-in-Java

396. Rotate Function

Medium

You are given an integer array nums of length n.

Assume arrk to be an array obtained by rotating nums by k positions clock-wise. We define the rotation function F on nums as follow:

• F(k) = 0 * arrk[0] + 1 * arrk[1] + ... + (n - 1) * arrk[n - 1].

Return the maximum value of F(0), F(1), ..., F(n-1).

The test cases are generated so that the answer fits in a 32-bit integer.

Example 1:

Input: nums = [4,3,2,6]

Output: 26

Explanation:

F(0) = (0 * 4) + (1 * 3) + (2 * 2) + (3 * 6) = 0 + 3 + 4 + 18 = 25

F(1) = (0 * 6) + (1 * 4) + (2 * 3) + (3 * 2) = 0 + 4 + 6 + 6 = 16

F(2) = (0 * 2) + (1 * 6) + (2 * 4) + (3 * 3) = 0 + 6 + 8 + 9 = 23

F(3) = (0 * 3) + (1 * 2) + (2 * 6) + (3 * 4) = 0 + 2 + 12 + 12 = 26

So the maximum value of F(0), F(1), F(2), F(3) is F(3) = 26.

Example 2:

Input: nums = [100]

Output: 0

Constraints:

• n == nums.length
• 1 <= n <= 105
• -100 <= nums[i] <= 100

Solution

public class Solution {
    public int maxRotateFunction(int[] nums) {
        int allSum = 0;
        int len = nums.length;
        int f = 0;
        for (int i = 0; i < len; i++) {
            f += i * nums[i];
            allSum += nums[i];
        }
        int max = f;
        for (int i = len - 1; i >= 1; i--) {
            f = f + allSum - len * nums[i];
            max = Math.max(f, max);
        }
        return max;
    }
}

This site is open source. Improve this page.