I don’t understand the output of this recursion. Can someone please help me? (flowchart will definitely help me understand..)
JavaScript
x
public class Stars {
public static void printNChars (int n, char c) {
for (int j=0; j<n; j++) {
System.out.print(c);
}
}
public static void printNStars (int n) {
printNChars (n, '*');
System.out.println();
}
public static void triangle(int n) {
if (n==1) {
printNStars(1);
}
else {triangle (n-1);
printNStars(n);
}
}
public static void main (String [] args) {
triangle(5);
}
}
public static void main (String [] args) {
triangle(5);
}
}
Output of the code above:
JavaScript
*
* *
* * *
* * * *
* * * * *
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Answer
It works in the following way:
JavaScript
triangle(n):
triangle(n-1)
printNStars(n)
which can be translated into:
JavaScript
triangle(n)
when previous rows are printed
print nth row.
there is also an exit rule. If n is 1, don’t draw previous rows. Just print one star.
The executions will be in the following order:
JavaScript
n = 4:
triangle(4)
triangle(3)
triangle(2)
triangle(1)
printNStars(1)
System.out.println()
printNStars(2)
System.out.println()
printNStars(3)
System.out.println()
printNStars(4)
System.out.println()