3229. Minimum Operations to Make Array Equal to Target

You are given two positive integer arrays nums and target, of the same length.

In a single operation, you can select any subarray of nums and increment or decrement each element within that subarray by 1.

Return the minimum number of operations required to make nums equal to the array target.

Example 1:

Input: nums = [3,5,1,2], target = [4,6,2,4]

Output: 2

Explanation:

We will perform the following operations to make nums equal to target: - Increment nums[0..3] by 1, nums = [4,6,2,3]. - Increment nums[3..3] by 1, nums = [4,6,2,4].

Example 2:

Input: nums = [1,3,2], target = [2,1,4]

Output: 5

Explanation:

We will perform the following operations to make nums equal to target: - Increment nums[0..0] by 1, nums = [2,3,2]. - Decrement nums[1..1] by 1, nums = [2,2,2]. - Decrement nums[1..1] by 1, nums = [2,1,2]. - Increment nums[2..2] by 1, nums = [2,1,3]. - Increment nums[2..2] by 1, nums = [2,1,4].

Constraints:

• 1 <= nums.length == target.length <= 105
• 1 <= nums[i], target[i] <= 108

Solution:

class Solution {
    public long minimumOperations(int[] nums, int[] target) {
        var n = nums.length;
        long incr = 0, decr = 0, ops = 0;

        for (var i = 0; i < n; i++) {
            var diff = target[i] - nums[i];

            if (diff > 0) {
                if (incr < diff)
                    ops += diff - incr;
                incr = diff;
                decr = 0;
            } else if (diff < 0) {
                if (diff < decr)
                    ops += decr - diff;
                decr = diff;
                incr = 0;
            } else {
                incr = decr = 0;
            }
        }

        return ops;
    }
}