LeetCode in Kotlin

330. Patching Array

Hard

Given a sorted integer array nums and an integer n, add/patch elements to the array such that any number in the range [1, n] inclusive can be formed by the sum of some elements in the array.

Return the minimum number of patches required.

Example 1:

Input: nums = [1,3], n = 6

Output: 1 Explanation: Combinations of nums are [1], [3], [1,3], which form possible sums of: 1, 3, 4. Now if we add/patch 2 to nums, the combinations are: [1], [2], [3], [1,3], [2,3], [1,2,3]. Possible sums are 1, 2, 3, 4, 5, 6, which now covers the range [1, 6]. So we only need 1 patch.

Example 2:

Input: nums = [1,5,10], n = 20

Output: 2 Explanation: The two patches can be [2, 4].

Example 3:

Input: nums = [1,2,2], n = 5

Output: 0

Constraints:

• 1 <= nums.length <= 1000
• 1 <= nums[i] <= 104
• nums is sorted in ascending order.
• 1 <= n <= 231 - 1

Solution

class Solution {
    fun minPatches(nums: IntArray, n: Int): Int {
        var res = 0
        var sum: Long = 0
        var i = 0
        while (sum < n) {
            // required number
            val req = sum + 1
            if (i < nums.size && nums[i] <= req) {
                sum += nums[i++].toLong()
            } else {
                sum += req
                res++
            }
        }
        return res
    }
}

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