数据结构练习（09）排序数组中和为给定值的两个数字

http://zhedahht.blog.163.com/blog/static/2541117420072143251809/

关于扩展1，只能想到O(n²)的思路，相信肯定还会有更优的解法，找到了再更新。

bool find2number(int data[], unsigned int len, int sum, int& num1, int& num2)
{
    bool found = false;
    if (len < 1)
        return found;

    int ahead = len - 1;
    int behind = 0;

    while (behind < ahead)
    {
        if (data[behind] + data[ahead] == sum)
        {
            num1 = data[behind];
            num2 = data[ahead];
            found = true;
            break;
        }
        else if (data[behind] + data[ahead] > sum)
            --ahead;
        else
            ++behind;
    }
    return found;
}