CS99
Fundamental Programming Concepts
Summer 2001

 

Prelim 2: Solutions

Tracing Output

TokenReader in = new TokenReader( System.in );
int p = in.readInt();
int d = 0;
int n = 0;
while ( p > 1 ) {
      d = 2;
      while (  ( p % d) != 0 )
         d = d + 1;
      if ( d == p )
         n = n + 1;
      p = p - 1;
}
System.out.println();

p: 5               4   3       2     1
d:   0   2 3 4 5     2   2 3     2    
n:     0         1           2     3  

Part 2: Dangling Elses & Formatting Code

Part A properly indented:

if ( x < 10 )
   System.out.print( "!!!" );
if ( y > 10 )
   System.out.println( "***" );
else
   System.out.print( "###" );
System.out.println( "$$$" );

Output for Part A:

x=9, y=11:

!!!***
$$$		 x=11, y = 9:

###$$$

 

Part B properly indented:

if ( x > 10 ) {                                                    
   if ( y < 10 )
      System.out.println( "***" );
}
else {
   System.out.println( "###" );
   System.out.println( "$$$" );
}

Output for Part B:

x=9, y=11:

###
$$$		 x=11, y = 9:

***

TokenReader in = new TokenReader( System.in );
int n = in.readInt();

// other declarations
int stars;

Solution 1.

while ( n > 0 ) {
   stars = in.readInt();
   while ( stars > 0 ) {
      System.out.print("*");
      stars--;
   }
   n--;
}

Solution 2.

// other declarations
int stars;
int count = 1;
int countStars;
while ( count <= n ) {
   stars = in.readInt();
   countStars = 1;
   while( countStars <= stars ) {
      System.out.print("*");
      countStars++;
   }
   count++;
}

Part 4: Determining Output [10 points]

Output:

6
3
1