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

分析：这道题是二分搜索算法，在结束的时候没有找到target，则left指向小于target的最大整数，right指向大于target的最小整数。如果找到了target，直接输出left。

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