1674. Minimum Moves to Make Array Complementary

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
```

Constraints:

• `n == nums.length`
• `2 <= n <= 105`
• `1 <= nums[i] <= limit <= 105`
• `n` is even.

1674. Minimum Moves to Make Array Complementary
``````struct Solution;

impl Solution {
fn min_moves(nums: Vec<i32>, limit: i32) -> i32 {
let n = nums.len();
let limit = limit as usize;
let mut delta = vec![0; limit * 2 + 2];
for i in 0..n / 2 {
let a = nums[i] as usize;
let b = nums[n - 1 - i] as usize;
delta[2] += 2;
delta[a.min(b) + 1] -= 1;
delta[a + b] -= 1;
delta[a + b + 1] += 1;
delta[a.max(b) + limit + 1] += 1;
}

let mut res = std::i32::MAX;
let mut cur = 0;
for sum in 2..=limit * 2 {
cur += delta[sum];
res = res.min(cur);
}
res
}
}

#[test]
fn test() {
let nums = vec![1, 2, 4, 3];
let limit = 4;
let res = 1;
assert_eq!(Solution::min_moves(nums, limit), res);
let nums = vec![1, 2, 2, 1];
let limit = 2;
let res = 2;
assert_eq!(Solution::min_moves(nums, limit), res);
let nums = vec![1, 2, 1, 2];
let limit = 2;
let res = 0;
assert_eq!(Solution::min_moves(nums, limit), res);
}
``````