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

C++实现代码：

#include<iostream>
using namespace std;

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

int main()
{
    Solution s;
    int A[10]={3,5,7,8,12,34,65,89,98,100};
    cout<<s.searchInsert(A,10,300)<<endl;
}

 使用二分法改进后的代码：

    int searchInsert(int A[], int n, int target) {
        if(n<=0)
            return 0;
        int left=0;
        int right=n-1;
        while(left<=right)
        {
            int mid=(left+right)/2;
            if(A[mid]==target)
                return mid;
            else if(A[mid]<target)
                left=mid+1;
            else
                right=mid-1;
        }
        return left;
    }