LeetCode 035. Search Insert Position

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

查找問題,有序數組,很自然使用二分查找,關鍵是本題不光是要實現查找功能,還需要找出插入的位置。

二分查找運行完之後low指針指向的是大於target的最小的數,high指針指向的是小於target的最大的數

因此運行完之後,返回low指針即可。

class Solution 
{
public:
    int searchInsert(int A[], int n, int target) 
    {
        int low, high, mid;
        low = 0;
        high = n-1;
        while(low<=high)
        {
            mid = (low+high)/2;
            if(target > A[mid])
                low = mid+1;
            else if(target < A[mid])
                high = mid-1;
            else if(target == A[mid])
                return mid;
        }
        return low;
    }
};


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