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

 

注意边界条件

class Solution {
public:
    int searchInsert(int A[], int n, int target) {
        if(target <= A[0])return 0;
        if(target > A[n-1])return n;
        
        return bisearch(A , 0 , n-1 , target);
    }
    
    int bisearch(int a[] , int begin  , int end ,int target)
    {
        if(target <= a[begin])return begin ;
        if(target > a[end])return end+1;
        
        int mid = (begin + end)/2;
        if(a[mid] == target) return mid;
        if(a[mid] < target)return bisearch(a,mid+1, end,target);
        if(a[mid] > target)return bisearch(a,begin , mid - 1, target);
    }
};