# 66. Plus One

#### Question

Given a non-negative integer represented as a non-empty array of digits, plus one to the integer.

You may assume the integer do not contain any leading zero, except the number 0 itself.

The digits are stored such that the most significant digit is at the head of the list.

#### What the question really means

Input | Output |
---|---|

[2, 3, 5] | [2, 3, 6] |

[9, 9] | [1, 0, 0] |

[0] | [1] |

#### Pseudo code

- Loop through the given array from tail
- If the current digit is less than 9, add 1 and return
- If the current digit is 9, set it to 0
- Add
`[1]`

to the head of the array and return

#### Playground

See the Pen 66. Plus One by Cherry Wang (@chryw) on CodePen.