Leetcode 35. 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.

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

 

思路： 通过观察可以发现，这一题其实就是要求array中>=target的第一个元素的位置。注意要将right设置成len(array)，因为如果array中没有>=target的数，最后的情况是left=right=len(array)。

class Solution(object):
    def searchInsert(self, nums, target):
        """
        :type nums: List[int]
        :type target: int
        :rtype: int
        """
        
        if not nums:
            return 0
            
        n = len(nums)
        left, right = 0, n
        
        while left < right:
            mid = left + (right - left)/2
            if nums[mid] >= target:
                right = mid
            else:
                left = mid + 1
        
        return left