34. Search for a Range【M】【76】

Given a sorted array of integers, find the starting and ending position of a given target value.

Your algorithm's runtime complexity must be in the order of O(log n).

If the target is not found in the array, return [-1, -1].

For example,
Given [5, 7, 7, 8, 8, 10] and target value 8,
return [3, 4].

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用二分法……

看到别人用的一个小技巧，

Search for the position target-0.5 and target+0.5

class Solution(object):    def searchRange(self, nums, target):        if target > nums[-1] or target < nums[0]:            return [-1,-1]        try:            nums.index(target)        except:            return [-1,-1]        start = 0        end = len(nums) - 1        mid = 0        while start <= end:            mid = (start + end) / 2            #print start,mid,end            if target == nums[mid]:                #print mid                break            elif target > nums[mid]:                start = mid + 1            else:                end = mid - 0        if nums[mid] != target:            return [-1,-1]        res_start = mid        res_end = mid        while res_start > 0 and nums[res_start-1] == target:            res_start -= 1        while res_end < len(nums) - 1 and nums[res_end+1] == target:            res_end += 1        return [res_start,res_end]