[LeetCode] Search Insert Position 解题报告

最新推荐文章于 2020-02-23 17:06:04 发布

原创最新推荐文章于 2020-02-23 17:06:04 发布 · 181 阅读

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本文介绍了一道二分查找变种问题的解决方法，该问题要求在已排序的数组中找到目标值的位置，若不存在则返回目标值应该插入的位置。文章提供了详细的解题思路及C/C++代码实现。

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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.

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

» Solve this problem

[解题思路]
跟经典的二分查找相比，只是多了一个条件：
if(mid>left && A[mid]>target && A[mid-1]<target)

[Code]

1:  int searchInsert(int A[], int n, int target) {  
2:      // Start typing your C/C++ solution below  
3:      // DO NOT write int main() function  
4:      int l=0, r=n-1;  
5:      while(l<=r)  
6:      {  
7:        int mid = (l+r)/2;  
8:        if(A[mid] == target) return mid;  
9:        if(mid>l && A[mid]>target && A[mid-1]<target ) return mid;  
10:        if(A[mid] > target)  
11:        {  
12:          r= mid-1;  
13:        }  
14:        else  
15:        {  
16:          l=mid+1;  
17:        }        
18:      }  
19:      return l;  
20:    }