README.md

2541. Minimum Operations to Make Array Equal II

You are given two integer arrays nums1 and nums2 of equal length n and an integer k. You can perform the following operation on nums1:

• Choose two indexes i and j and increment nums1[i] by k and decrement nums1[j] by k. In other words, nums1[i] = nums1[i] + k and nums1[j] = nums1[j] - k.

nums1 is said to be equal to nums2 if for all indices i such that 0 <= i < n, nums1[i] == nums2[i].

Return the minimum number of operations required to make nums1 equal to nums2. If it is impossible to make them equal, return -1.

Example 1:

Input: nums1 = [4,3,1,4], nums2 = [1,3,7,1], k = 3
Output: 2
Explanation: In 2 operations, we can transform nums1 to nums2.
1st operation: i = 2, j = 0. After applying the operation, nums1 = [1,3,4,4].
2nd operation: i = 2, j = 3. After applying the operation, nums1 = [1,3,7,1].
One can prove that it is impossible to make arrays equal in fewer operations.

Example 2:

Input: nums1 = [3,8,5,2], nums2 = [2,4,1,6], k = 1
Output: -1
Explanation: It can be proved that it is impossible to make the two arrays equal.

Constraints:

• n == nums1.length == nums2.length
• 2 <= n <= 105
• 0 <= nums1[i], nums2[j] <= 109
• 0 <= k <= 105

Solutions (Rust)

1. Solution

impl Solution {
    pub fn min_operations(nums1: Vec<i32>, nums2: Vec<i32>, k: i32) -> i64 {
        if k == 0 {
            if (0..nums1.len()).all(|i| nums1[i] == nums2[i]) {
                return 0;
            } else {
                return -1;
            }
        }

        let mut inc = 0;
        let mut dec = 0;

        for i in 0..nums1.len() {
            if nums1[i] < nums2[i] && (nums2[i] - nums1[i]) % k == 0 {
                inc += ((nums2[i] - nums1[i]) / k) as i64;
            } else if nums1[i] > nums2[i] && (nums1[i] - nums2[i]) % k == 0 {
                dec += ((nums1[i] - nums2[i]) / k) as i64;
            } else if nums1[i] != nums2[i] {
                return -1;
            }
        }

        if inc == dec {
            inc
        } else {
            -1
        }
    }
}