Medium
You are given an integer array nums
of even length n
and an integer limit
. In one move, you can replace any integer from nums
with another integer between 1
and limit
, inclusive.
The array nums
is complementary if for all indices i
(0-indexed), nums[i] + nums[n - 1 - i]
equals the same number. For example, the array [1,2,3,4]
is complementary because for all indices i
, nums[i] + nums[n - 1 - i] = 5
.
Return the minimum number of moves required to make nums
complementary.
Example 1:
Input: nums = [1,2,4,3], limit = 4
Output: 1
Explanation: In 1 move, you can change nums to [1,2,2,3] (underlined elements are changed).
nums[0] + nums[3] = 1 + 3 = 4.
nums[1] + nums[2] = 2 + 2 = 4.
nums[2] + nums[1] = 2 + 2 = 4.
nums[3] + nums[0] = 3 + 1 = 4.
Therefore, nums[i] + nums[n-1-i] = 4 for every i, so nums is complementary.
Example 2:
Input: nums = [1,2,2,1], limit = 2
Output: 2
Explanation: In 2 moves, you can change nums to [2,2,2,2]. You cannot change any number to 3 since 3 > limit.
Example 3:
Input: nums = [1,2,1,2], limit = 2
Output: 0
Explanation: nums is already complementary.
Constraints:
n == nums.length
2 <= n <= 105
1 <= nums[i] <= limit <= 105
n
is even.class Solution {
fun minMoves(nums: IntArray, limit: Int): Int {
val delta = IntArray(2 * limit + 2)
val n = nums.size
for (i in 0 until n / 2) {
val a = nums[i]
val b = nums[n - 1 - i]
delta[2] += 2
delta[Math.min(a, b) + 1]--
delta[a + b]--
delta[a + b + 1]++
delta[Math.max(a, b) + limit + 1]++
}
var res = 2 * n
var curr = 0
for (i in 2..2 * limit) {
curr += delta[i]
res = Math.min(res, curr)
}
return res
}
}