228.Summary Ranges
===
###### tags: `Easy`,`Array`
[228. Summary Ranges](https://leetcode.com/problems/summary-ranges/)
### 題目描述
You are given a **sorted unique** integer array `nums`.
A **range** `[a,b]` is the set of all integers from `a` to `b` (inclusive).
Return *the **smallest sorted** list of ranges that **cover all the numbers in the array exactly**.* That is, each element of `nums` is covered by exactly one of the ranges, and there is no integer `x` such that `x` is in one of the ranges but not in `nums`.
Each range `[a,b]` in the list should be output as:
- `"a->b"` if `a != b`
- `"a"` if `a == b`
### 範例
**Example 1:**
```
Input: nums = [0,1,2,4,5,7]
Output: ["0->2","4->5","7"]
Explanation: The ranges are:
[0,2] --> "0->2"
[4,5] --> "4->5"
[7,7] --> "7"
```
**Example 2:**
```
Input: nums = [0,2,3,4,6,8,9]
Output: ["0","2->4","6","8->9"]
Explanation: The ranges are:
[0,0] --> "0"
[2,4] --> "2->4"
[6,6] --> "6"
[8,9] --> "8->9"
```
**Constraints**:
* 0 <= nums.length <= 20
* -2^31^ <= `nums[i]` <= 2^31^ - 1
* All the values of `nums` are **unique**.
* `nums` is sorted in ascending order.
### 解答
### Reference
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