[二分法模板] 34. Find First and Last

Description

给定sorted list & target num,返第一次&最后一次出现的位置

复习Binary Search模板
class Solution:  
    def searchRange(self, nums: List[int], target: int) -> List[int]:
        def search(nums,target,first=True):
            start = 0
            end = len(nums)-1
            while start +1 < end:
                mid = (start+end)//2
                if target > nums[mid]:
                    start = mid
                elif target < nums[mid]:
                    end = mid
                else:
                    if first is True:
                        end = mid
                    else:
                        start = mid
            if first is True:
                if nums[start] == target:
                    res = start
                elif nums[end] ==target:
                    res = end 
                else:
                    res = -1
            else:
                
                if nums[end] ==target:
                    res = end 
                elif nums[start] == target:
                    res = start
                else:
                    res = -1
                
            return res
        
        if len(nums)==0:
            return [-1,-1]
        
        fin_start = search(nums,target,first=True)
        fin_end = search(nums,target,first=False)
            
        return [fin_start,fin_end]