【LeetCode】Search Insert Position

最新推荐文章于 2025-10-27 10:59:34 发布

原创最新推荐文章于 2025-10-27 10:59:34 发布 · 468 阅读

0 ·

CC 4.0 BY-SA版权

文章标签：

#二分查找 #leetcode #search

LeetCode 专栏收录该内容

86 篇文章

订阅专栏

本文深入解析了C++中关于在已排序数组中搜索插入位置的问题，提供了详细的二分查找变形算法分析，并附上了实际代码示例，帮助读者理解和实现这一核心算法。

题目描述

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

题目分析

二分查找的变形，不多说

总结

理解在不存在时的返回值应该是多少。

代码示例


/*
编译环境CFree 5.0
博客地址：http://blog.youkuaiyun.com/Snowwolf_Yang
*/
#include 
   
    

using namespace std;

#if 0 
class Solution {
public:
    int searchInsert(int A[], int n, int target) {
    	if(n == 0)	return 0;
        if(n == 1)
        {
        	if(A[0] < target) 	return 1;
        	else 				return 0;
		}
		int mid = n/2;
		if(A[mid]
    
     target)
				return searchInsert(&A[0],mid,target);
		else
			return mid;
    }
};
#elif 1
class Solution {
public:
    int searchInsert(int A[], int n, int target) {
    	if(n == 0)	return 0;
		int start = 0, end = n - 1;
		while(start <= end)
		{
			int mid = (start + end)/2;
			if(A[mid]
     
      target)
				end = mid - 1;
			else 
				return mid;
		}
		return start;					//这一点需要理解透彻 
    }
};
#endif
void test0()
{
	int a[] = {1,3,5,6}; 
	int n = 4;
	int target = 5;
	int expected = 2;
	Solution so;
	if(so.searchInsert(a,n,target) == expected)
		printf("---------------------passed\n");
	else
		printf("---------------------failed\n");	
}
void test1()
{
	int a[] = {1,3,5,6}; 
	int n = 4;
	int target = 2;
	int expected = 1;
	Solution so;
	if(so.searchInsert(a,n,target) == expected)
		printf("---------------------passed\n");
	else
		printf("---------------------failed\n");	
}
void test2()
{
	int a[] = {1,3,5,6}; 
	int n = 4;
	int target = 7;
	int expected = 4;
	Solution so;
	if(so.searchInsert(a,n,target) == expected)
		printf("---------------------passed\n");
	else
		printf("---------------------failed\n");	
}
void test3()
{
	int a[] = {1,3,5,6}; 
	int n = 4;
	int target = 0;
	int expected = 0;
	Solution so;
	if(so.searchInsert(a,n,target) == expected)
		printf("---------------------passed\n");
	else
		printf("---------------------failed\n");	
}
void test4()
{
	int a[] = {1,3}; 
	int n = 2;
	int target = 0;
	int expected = 0;
	Solution so;
	if(so.searchInsert(a,n,target) == expected)
		printf("---------------------passed\n");
	else
		printf("---------------------failed\n");	
}
int main()
{
	test0();
	test1();
	test2();
	test3();
	test4();
	return 0;
}