LeetCode:Search Insert Position

最新推荐文章于 2021-05-03 16:49:38 发布

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本文探讨了在已排序数组中查找目标值插入位置的三种方法：利用Python内置函数、暴力求解及二分查找法。通过具体示例，详细解释了每种方法的实现过程。

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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.

Example 1:

Input: [1,3,5,6], 5
Output: 2
Example 2:

Input: [1,3,5,6], 2
Output: 1

第一个思路也是调用python内置的函数，先把目标值插入进去，再进行排序，得到该值的索引：

class Solution:
    def searchInsert(self, nums: List[int], target: int) -> int:
        nums.append(target)
        nums.sort()
        return nums.index(target)

第二个思路就是暴力求解,循环找出不小于插入值的索引即可.:

class Solution:
    def searchInsert(self, nums: List[int], target: int) -> int:
        for i in range(len(nums)):
            if nums[i] >= target:
                return i
        # return len(nums)
        return i + 1

第三个思路是使用二分查找法:

class Solution:
    def searchInsert(self, nums: List[int], target: int) -> int:
        left = 0
        right = len(nums) - 1
        while left <= right:
            mid = left + (right - left) // 2 
            if nums[mid] == target:return mid
            elif nums[mid] < target:
                left = mid + 1
            else:
                right = mid - 1
        return left

class Solution:
    def searchInsert(self, nums: List[int], target: int) -> int:
        left = 0
        right = len(nums)
        while left < right:
            mid = left + (right - left) // 2 
            if nums[mid] < target:
                left = mid + 1
            else:
                right = mid
        return left