1- ### 34. Search for a Range
1+ # 34. Find First and Last Position of Element in Sorted Array
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3+ ** <font color =red >难度: Medium</font >**
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5+ ## 刷题内容
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5- 题目:
7+ > 原题连接
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7- https://leetcode.com/problems/search-for-a-range /
9+ * https://leetcode.com/problems/find-first-and-last-position-of-element-in-sorted-array/description /
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11+ > 内容描述
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13+ ```
14+ Given an array of integers nums sorted in ascending order, find the starting and ending position of a given target value.
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16+ Your algorithm's runtime complexity must be in the order of O(log n).
17+
18+ If the target is not found in the array, return [-1, -1].
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11- 难度 : Medium
20+ Example 1:
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22+ Input: nums = [5,7,7,8,8,10], target = 8
23+ Output: [3,4]
24+ Example 2:
25+
26+ Input: nums = [5,7,7,8,8,10], target = 6
27+ Output: [-1,-1]
28+ ```
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30+ ## 解题方案
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15- 思路:
32+ > 思路 1
33+ ****** - 时间复杂度: O(lgN)****** - 空间复杂度: O(1)******
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1735二分法,先找``` target ``` 出现的左边界,判断是否有``` target ``` 后再判断右边界
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3149AC 代码
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33- 34- 35- 3651``` python
3752class Solution (object ):
3853 def searchRange (self nums , target ):
@@ -41,7 +56,8 @@ class Solution(object):
4156 :type target: int
4257 :rtype: List[int]
4358 """
44- if not nums : return [- 1 , - 1 ]
59+ if not nums or len (nums) == 0 :
60+ return [- 1 , - 1 ]
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4662 res = []
4763 l, r = 0 , len (nums)- 1
@@ -57,6 +73,7 @@ class Solution(object):
5773 r = mid - 1
5874 if not res:
5975 return [- 1 , - 1 ]
76+ 6077 # search for right bound
6178 r = len (nums)- 1
6279 while l <= r:
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