[LeetCode]题解（python）：035-Search Insert Position

https://leetcode.com/problems/search-insert-position/

Given a sorted array and a target value, return the index if the target is found. If not, return the index where it would be if it were inserted in order.

You may assume no duplicates in the array.

Output: the index if the target is found. If not, return the index where it would be if it were inserted in order.

Conditions:找到target所在的位置或者应该插入的位置

Here are few examples.
[1,3,5,6], 5 → 2
[1,3,5,6], 2 → 1
[1,3,5,6], 7 → 4
[1,3,5,6], 0 → 0

1. 如果target大于nums[first]，返回first + 1
2. 反之返回first

注意到在二分法当中first可能会加1溢出数组，所以在上面步骤当中要在比较前加入判断first是否溢出数组

 1 _author_ = "YE"
 2 # -*- coding:utf-8 -*-
 3
 4 class Solution(object):
 5     def searchInsert(self, nums, target):
 6         """
 7         :type nums: List[int]
 8         :type target: int
 9         :rtype: int
10         """
11         len1 = len(nums)
12         first = 0
13         last = len1
14         while first < last:
15             mid = (first + last) // 2
16             if nums[mid] == target:
17                 return mid
18             elif nums[mid] < target:
19                 first = mid + 1
20             else:
21                 last = mid - 1
22         # print(first,last)
23         if first < len1 and nums[first] < target:
24             return first + 1
25         return first
26
27 s = Solution()
28 nums = [1,3]
29 target = 2
30 print(s.searchInsert(nums, target))