对分查找

给定一个整数X和整数A0,A1,…,AN-1,后者已经预先排序并存在内存中，求使得Ai=X的下标i，如果X不在数据中，则返回i=-1。

int BinarySearch (const ElementType A[], ElementType x, int N)
{
    int Low, Mid, High;

    Low = 0; High = N - 1;
    while (Low <= High)
    {
        Mid = (Low + High) / 2;
        if (A[Mid] < x)
            Low = Mid + 1;
        else if (A[Mid] > x)
            High = Mid - 1;
        else
            return Mid; //Found     
    }
    return NotFound //NotFound is defined as -1
}

欧几里得算法

计算两个整数的最大公因数（Gcd），通过连续计算余数直到余数是0为止，最后的非零余数就是最大公因数。

unsigned int Gcd (unsigned int M, unsigned int N)
{
    unsigned int Rem;

    while (N > 0)
    {
        Rem = M % N;
        M = N;
        N = Rem;
    }
    return M;
}

幂运算

递归算X^N

long int Pow (long int X；unsigned int N)
{
    if (N == 0)
        return 1;
    if (IsEven(N))
        return Pow (X * X, N / 2);
    else
        return Pow (X * X, N / 2) * X;
}