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107 lines
2.1 KiB
Markdown
107 lines
2.1 KiB
Markdown
# [228. Summary Ranges](https://leetcode.com/problems/summary-ranges/)
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## 题目
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You are given a **sorted unique** integer array `nums`.
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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`.
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Each range `[a,b]` in the list should be output as:
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- `"a->b"` if `a != b`
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- `"a"` if `a == b`
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**Example 1:**
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```
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Input: nums = [0,1,2,4,5,7]
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Output: ["0->2","4->5","7"]
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Explanation: The ranges are:
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[0,2] --> "0->2"
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[4,5] --> "4->5"
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[7,7] --> "7"
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```
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**Example 2:**
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```
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Input: nums = [0,2,3,4,6,8,9]
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Output: ["0","2->4","6","8->9"]
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Explanation: The ranges are:
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[0,0] --> "0"
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[2,4] --> "2->4"
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[6,6] --> "6"
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[8,9] --> "8->9"
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```
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**Example 3:**
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```
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Input: nums = []
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Output: []
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```
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**Example 4:**
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```
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Input: nums = [-1]
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Output: ["-1"]
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```
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**Example 5:**
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```
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Input: nums = [0]
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Output: ["0"]
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```
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**Constraints:**
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- `0 <= nums.length <= 20`
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- `231 <= nums[i] <= 231 - 1`
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- All the values of `nums` are **unique**.
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- `nums` is sorted in ascending order.
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## 题目大意
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给定一个无重复元素的有序整数数组 nums 。
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返回 恰好覆盖数组中所有数字 的 最小有序 区间范围列表。也就是说，nums 的每个元素都恰好被某个区间范围所覆盖，并且不存在属于某个范围但不属于 nums 的数字 x 。
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列表中的每个区间范围 [a,b] 应该按如下格式输出：
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- "a->b" ，如果 a != b
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- "a" ，如果 a == b
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## 解题思路
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- 简单题。按照题意，用一个游标变量累加寻找连续的区间。一旦出现了中断，就按照题意格式输出。输出的规则有多种，带箭头的区间，单个元素区间，空区间。
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## 代码
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```go
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package leetcode
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import (
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"strconv"
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)
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func summaryRanges(nums []int) (ans []string) {
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for i, n := 0, len(nums); i < n; {
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left := i
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for i++; i < n && nums[i-1]+1 == nums[i]; i++ {
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}
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s := strconv.Itoa(nums[left])
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if left != i-1 {
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s += "->" + strconv.Itoa(nums[i-1])
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}
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ans = append(ans, s)
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}
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return
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}
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``` |