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剑指 Offer II 068. 查找插入位置

题目描述

给定一个排序的整数数组 nums 和一个整数目标值 target ，请在数组中找到 target ，并返回其下标。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

 

提示:

• 1 <= nums.length <= 104
• -104 <= nums[i] <= 104
• nums 为无重复元素的升序排列数组
• -104 <= target <= 104

 

注意：本题与主站 35 题相同： https://leetcode-cn.com/problems/search-insert-position/

解法

二分查找。

Python3

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

Java

class Solution {
    public int searchInsert(int[] nums, int target) {
        int left = 0, right = nums.length;
        while (left < right) {
            int mid = (left + right) >>> 1;
            if (nums[mid] >= target) {
                right = mid;
            } else {
                left = mid + 1;
            }
        }
        return left;
    }
}

C++

class Solution {
public:
    int searchInsert(vector<int>& nums, int target) {
        int left = 0, right = nums.size();
        while (left < right)
        {
            int mid = left + right >> 1;
            if (nums[mid] >= target) right = mid;
            else left = mid + 1;
        }
        return left;
    }
};

Go

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

JavaScript

/**
 * @param {number[]} nums
 * @param {number} target
 * @return {number}
 */
var searchInsert = function (nums, target) {
    let left = 0;
    let right = nums.length;
    while (left < right) {
        const mid = (left + right) >> 1;
        if (nums[mid] >= target) {
            right = mid;
        } else {
            left = mid + 1;
        }
    }
    return left;
};

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