動機

複習lowerbound

Problem

Given a sorted array of distinct integers 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 must write an algorithm with O(log n) runtime complexity.

 

Example 1:

Input: nums = [1,3,5,6], target = 5Output: 2

Example 2:

Input: nums = [1,3,5,6], target = 2Output: 1

Example 3:

Input: nums = [1,3,5,6], target = 7Output: 4

Example 4:

Input: nums = [1,3,5,6], target = 0Output: 0

Example 5:

Input: nums = [1], target = 0Output: 0

 

Constraints:

  • 1 <= nums.length <= 104
  • -104 <= nums[i] <= 104
  • nums contains distinct values sorted in ascending order.
  • -104 <= target <= 104

Sol

class Solution:
    def searchInsert(self, ns: List[int], t: int) -> int:
        i, j = [0, len(ns)]
        while i < j:
            mid = i + (j-i)//2 # 如果是python可以直接寫(i+j)//2
            if ns[mid] < t:
                i = mid+1
            else:
                j = mid
        return i