Search Insert Position（数组插入元素）

二分查找算法实现

最新推荐文章于 2023-06-27 23:07:57 发布

Cuphrody

最新推荐文章于 2023-06-27 23:07:57 发布

阅读量462

点赞数

CC 4.0 BY-SA版权

分类专栏： LeetCode OJ 文章标签： C++ algorithm 二分查找

本文链接：https://blog.youkuaiyun.com/cuphrody/article/details/12887511

LeetCode OJ 专栏收录该内容

71 篇文章

订阅专栏

本文介绍了一种在已排序数组中查找目标值的二分查找算法，并提供了C++实现代码。该算法能在O(logn)的时间复杂度内找到目标值或确定其插入位置。

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

简单的查找数字，用二分法，时间复杂度O(logn) 注意边界检查

class Solution {
public:
    int searchInsert(int A[], int n, int target) {
        // Note: The Solution object is instantiated only once and is reused by each test case.
        int start = 0, end = n - 1, mid = 0;
		while (start < end)
		{
			mid = (start + end) / 2;
			if (target == A[mid])
				return mid;
			else if (target > A[mid])
				start = mid + 1;
			else
				end = mid - 1;
		}
		return target > A[start] ? start + 1 : start;
    }
};