LeetCode in Kotlin

66. Plus One

Easy

You are given a large integer represented as an integer array digits, where each digits[i] is the ith digit of the integer. The digits are ordered from most significant to least significant in left-to-right order. The large integer does not contain any leading 0’s.

Increment the large integer by one and return the resulting array of digits.

Example 1:

Input: digits = [1,2,3]

Output: [1,2,4]

Explanation:

The array represents the integer 123.

Incrementing by one gives 123 + 1 = 124.

Thus, the result should be [1,2,4].

Example 2:

Input: digits = [4,3,2,1]

Output: [4,3,2,2]

Explanation:

The array represents the integer 4321.

Incrementing by one gives 4321 + 1 = 4322.

Thus, the result should be [4,3,2,2].

Example 3:

Input: digits = [9]

Output: [1,0]

Explanation:

The array represents the integer 9.

Incrementing by one gives 9 + 1 = 10.

Thus, the result should be [1,0].

Constraints:

Solution

class Solution {
    fun plusOne(digits: IntArray): IntArray {
        val num = 1
        var carry = 0
        var sum: Int
        for (i in digits.indices.reversed()) {
            sum = if (i == digits.size - 1) {
                digits[i] + carry + num
            } else {
                digits[i] + carry
            }
            carry = sum / 10
            digits[i] = sum % 10
        }
        if (carry != 0) {
            val ans = IntArray(digits.size + 1)
            ans[0] = carry
            System.arraycopy(digits, 0, ans, 1, ans.size - 1)
            return ans
        }
        return digits
    }
}