LeetCode[Array]: 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

很典型的二分查找，只需要注意一个问题即可：如果未找到，那么high必然在low的前一个，此时low才是应该返回的位置。这个仔细想一下不难想到。

我的C++代码实现如下：

int searchInsert(int A[], int n, int target) {
    int low = 0, high = n - 1;
    while (low <=  high) {
        int middle = (low + high) >> 1;
        if (A[middle] == target) return middle;
        else if (A[middle] > target) high = middle - 1;
        else low = middle + 1;
    }

    return low;
}