对分查找、欧几里得算法求最大公约数

  int BinarySearch(const int A[], int 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;
    }
    return NotFound;
 }

  unsigned Gcd(unsigned int M, unsigned int N)
  {
     unsigned int Rem;
     while(N > 0)
     {
        Rem = M % N;
        M = N;
        N = Rem;
     }
    return M;
 }