# 2022-06-25

## [66. Plus One](https://leetcode.com/problems/plus-one/)

### Description

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:**

* `1 <= digits.length <= 100`
* `0 <= digits[i] <= 9`
* `digits` does not contain any leading `0`'s.

### Solution

#### Approach #0

```go
func plusOne(digits []int) []int {
    digits[len(digits)-1]++
    for i := len(digits) - 1; i >= 0; i-- {
        if i > 0 {
            if digits[i] >= 10 {
                digits[i] -= 10
                digits[i-1]++
            }
        } else {
            if digits[i] >= 10 {
                digits[i] -= 10
                digits = append([]int{1}, digits...)
            }
        }
    }
    return digits
}
```