Question

[Java] Write a recursive function to print the following output based on "hello" as input.

hello
hell
hel
he
h
he
hel
hell
hello

Then modify the code above to change the output to right justified and remove letter on the left.
hello
ello
llo
lo
o
lo
llo
ello
hello

Answer 1

This is the forward hello code:
class RecurseHello
{
public static void printReducedString(String inp,int num)
{
int offset;
if (num < 0)
{
offset = 6 + num ;
}
else
{
offset = num;
}
System.out.println(inp.substring(0,offset));
if (num > 1 )
{
printReducedString(inp,num-1);

}
if (num < -1)
{
printReducedString(inp,num+1);
}
}

public static void main(String[] args)
{
printReducedString("hello",5);
printReducedString("hello",-4);
}
}

And this is the Backward hello code:
class BackHello
{
public static void printReducedString(String inp,int num)
{
int offset;
String offspace ="";
if (num < 0)
{
offset = 5 + num ;
}
else
{
offset = num;
}
for (int x = 0; x < offset ;x++)
{
offspace = offspace + " ";

}
if (offset != 5)
{
System.out.println(offspace + inp.substring(offset,5));
}
if (num > 0 )
{
printReducedString(inp,num-1);

}
if (num < -2)
{
printReducedString(inp,num+1);
}
}

public static void main(String[] args)
{
printReducedString("hello",-5);
printReducedString("hello",5);
}
}

There might be better ways to do this....

Answer 2

Hi, can you please explain your code? I dont really understand. My computer science teacher didn't really teach me anything.

Answer 3

Here is the code with some useful comments for RecurseHello. Sorry for the lack before.
Let me know if this helps.
class RecurseHello
{
public static void printReducedString(String inp,int num)
{
int offset;
// If the num argument is negative, offset the count by 1
// more than the size of the string
if (num < 0)
{
offset = 6 + num ;
}
else
{
// else use the num argument as offset
offset = num;
}
// This prints the substring of the inp variable
System.out.println(inp.substring(0,offset));

// If the num argument is greater than 0
// call the printReducedString with num-1
if (num > 1 )
{
printReducedString(inp,num-1);

}
// if the num argument is less than 0
// call the printReducedString with num + 1
if (num < -1)
{
printReducedString(inp,num+1);
}
// If it is 0, then let the function exit.
}

public static void main(String[] args)
{
//call recursive function to print string reducing
printReducedString("hello",5);
// call recursive function to print string increasing
printReducedString("hello",-4);
}
}

Answer 4

If that is confusing, please feel free to ask any questions.