國立暨南國際大學 102 學年度第二學期小考試卷

1. (10%) Determine whether the following code is correct or not.  If it is correct, predict its output.  If it is incorrect, point out the mistake(s).
   // Initialize a Matrix
   #include <iostream>
   
   int main()
   {
       unsigned short data[2][ ] = { { 1, 2, 3, 4}, {5, 6, 7, 8} };
       std::cout << data[1][1] << std::endl;
       return 0;
   }
   
   
   
2. (10%) Determine whether the following code is correct or not.  If it is correct, predict its output.  If it is incorrect, point out the mistake(s).
   
   // Matrix Multiplication
   #include <iostream>
   
   int main()
   {
       const unsigned short N = 3;
       unsigned short i, j, k;
       unsigned short A[N][N] = { { 1, 0, 1 },
                                  { 1, 1, 0 },
                                  { 0, 1, 1}
                                };
       unsigned short B[N][N] = { { 1, 1, 0 },
                                  { 0, 1, 1 },
                                  { 1, 0, 1 }
                                };
       unsigned short C[N][N];
   
       for (i=0; i<N; i++)        // Multiply
           for (j=0; j<N; j++)
               for (k=0; k<N; k++)
                   C[i][j] = A[i][k] * B[k][j];
   
       for (i=0; i<N; i++)        // Print out
       {
           for (j=0; j<N; j++)
               std::cout << C[i][j] << ' ';
           std::cout << std::endl;
       }
       return 0;
   }
   
   
3. (10%) Determine whether the following code is correct or not.  If it is correct, predict its output.  If it is incorrect, point out the mistake(s).
   
   // Substitution Cipher
   #include <iostream>
   
   int main()
   {
       char plaintext[] = "NCNU";
       char password[] = "UNIVERSITY";
       char alphabet[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
       char mapping[27];
       char c;
       unsigned short i, j, k;
      
       for (k=0, i=0; (c=password[i]) != '\0'; i++)    // Preparing the mapping table
       {
           if (alphabet[ c - 'A' ] != 0)
           {
               mapping[k++] = c;
               alphabet[ c - 'A' ] = 0;
           }
       }
       for (j=0; k<26; )
       {
           while (alphabet[j] == 0) j++;
           mapping[k++] = alphabet[j++];
       }
       mapping[k] = '\0';
       // std::cout << "DEBUG - " << mapping << std::endl;
   
       for (i=0; (c=plaintext[i]) != '\0'; i++)
           std::cout << mapping[ c - 'A' ];
       std::cout << std::endl;
   
       return 0;
   }