0035-leetcode算法实现之搜索插入顺序-search-insert-position-python&golang实现

给定一个排序数组和一个目标值，在数组中找到目标值，并返回其索引。如果目标值不存在于数组中，返回它将会被按顺序插入的位置。

请必须使用时间复杂度为 O(log n) 的算法。

示例 1:

输入: nums = [1,3,5,6], target = 5
输出: 2
示例 2:

输入: nums = [1,3,5,6], target = 2
输出: 1
示例 3:

输入: nums = [1,3,5,6], target = 7
输出: 4
示例 4:

输入: nums = [1,3,5,6], target = 0
输出: 0
示例 5:

输入: nums = [1], target = 0
输出: 0

来源：力扣（LeetCode）
链接：https://leetcode-cn.com/problems/search-insert-position

python

# 搜索插入顺序
class Solution:
    def searchInsert(self, nums: [int], target: int) -> int:
        n = len(nums)
        left, right = 0, n-1
        while left <= right:
            mid = left + ((right-left) >> 1)
            if target < nums[mid]:
                right = mid - 1
            elif target > nums[mid]:
                left = mid + 1
            else:
                return mid
        # 4种情况
        # 1.target在所有元素前 [0,-1]
        # 2.target等于某个元素 mid
        # 3.target介于某2个元素之间 [left, right] -> right+1
        # 4.target在所有元素后 同上
        return right + 1

    # 暴力法 时间O(n)，空间O(1)
    def searchInsert1(self, nums, target):
        """
        遍历解决3种情况，1.比首个元素小的，2.等于某个元素， 3.介于某两个元素之间
        :param nums:
        :param target:
        :return:
        """
        n = len(nums)

        for i in range(n):
            if nums[i] >= target:
                return i
        # 情况4，大于最后一个元素
        return n

if __name__ == "__main__":
    nums = [2,3,6,7,8,14,16]
    target1 = 0
    target2 = 9
    target3 = 8
    target4 = 18

    test = Solution()
    print(test.searchInsert1(nums, target1))
    print(test.searchInsert1(nums, target2))
    print(test.searchInsert1(nums, target3))
    print(test.searchInsert1(nums, target4))
    print('*'*20)
    print(test.searchInsert(nums, target1))
    print(test.searchInsert(nums, target2))
    print(test.searchInsert(nums, target3))
    print(test.searchInsert(nums, target4))

golang

package main

import "fmt"

func main() {
	nums := []int{2, 3, 6, 7, 8, 14, 16}
	target1 := 0
	res1 := searchInsert(nums, target1)
	fmt.Println(res1)
}

func searchInsert(nums []int, target int) int {
	var n int = len(nums)
	left := 0
	right := n - 1
	for left <= right {
		var mid int = left + (right-left)>>1
		if target > nums[mid] {
			left = mid + 1
		} else if target < nums[mid] {
			right = mid - 1
		} else {
			return mid
		}
	}

	return right + 1
}

func searchInsert1(nums []int, target int) int {
	var n int = len(nums)

	for i, v := range nums {
		if v >= target {
			return i
		}
	}

	return n
}