Transcript Recursion - Introduction to Programming in Java

Recursive Factorial Demo
pubic class Factorial {
public static int fact(int n) {
if (n == 0) return 1;
else return n * fact(n-1);
}
public static void main(String[] args) {
System.out.println(fact(3));
}
}
Introduction to Computer Science
•
Robert Sedgewick and Kevin Wayne
•
http://www.cs.Princeton.EDU/IntroCS
n=3
environment
fact(3)
static int fact(int n) {
if (n == 0) return 1;
else return n * fact(n-1);
}
n=3
environment
fact(3)
static int fact(int n) {
if (n == 0) return 1;
else return n * fact(n-1);
}
n=3
environment
fact(3)
static int fact(int n) {
if (n == 0) return 1;
else return n * fact(n-1);
}
n=3
environment
n=2
environment
fact(3)
static int fact(int n) {
if (n == 0) return 1;
else return n * fact(n-1);
}
fact(2)
static int fact(int n) {
if (n == 0) return 1;
else return n * fact(n-1);
}
n=3
environment
n=2
environment
fact(3)
static int fact(int n) {
if (n == 0) return 1;
else return n * fact(n-1);
}
fact(2)
static int fact(int n) {
if (n == 0) return 1;
else return n * fact(n-1);
}
n=3
environment
n=2
environment
fact(3)
static int fact(int n) {
if (n == 0) return 1;
else return n * fact(n-1);
}
fact(2)
static int fact(int n) {
if (n == 0) return 1;
else return n * fact(n-1);
}
n=3
fact(3)
environment
n=2
environment
n=1
environment
static int fact(int n) {
if (n == 0) return 1;
else return n * fact(n-1);
}
fact(2)
static int fact(int n) {
if (n == 0) return 1;
else return n * fact(n-1);
}
fact(1)
static int fact(int n) {
if (n == 0) return 1;
else return n * fact(n-1);
}
n=3
fact(3)
environment
n=2
environment
n=1
environment
static int fact(int n) {
if (n == 0) return 1;
else return n * fact(n-1);
}
fact(2)
static int fact(int n) {
if (n == 0) return 1;
else return n * fact(n-1);
}
fact(1)
static int fact(int n) {
if (n == 0) return 1;
else return n * fact(n-1);
}
n=3
fact(3)
environment
n=2
environment
n=1
environment
static int fact(int n) {
if (n == 0) return 1;
else return n * fact(n-1);
}
fact(2)
static int fact(int n) {
if (n == 0) return 1;
else return n * fact(n-1);
}
fact(1)
static int fact(int n) {
if (n == 0) return 1;
else return n * fact(n-1);
}
n=3
fact(3)
environment
n=2
environment
n=1
environment
n=0
environment
static int fact(int n) {
if (n == 0) return 1;
else return n * fact(n-1);
}
fact(2)
static int fact(int n) {
if (n == 0) return 1;
else return n * fact(n-1);
}
fact(1)
static int fact(int n) {
if (n == 0) return 1;
else return n * fact(n-1);
}
fact(0)
static int fact(int n) {
if (n == 0) return 1;
else return n * fact(n-1);
}
n=3
fact(3)
environment
n=2
environment
n=1
environment
n=0
environment
static int fact(int n) {
if (n == 0) return 1;
else return n * fact(n-1);
}
fact(2)
static int fact(int n) {
if (n == 0) return 1;
else return n * fact(n-1);
}
fact(1)
static int fact(int n) {
if (n == 0) return 1;
else return n * fact(n-1);
}
fact(0)
static int fact(int n) {
if (n == 0) return 1;
else return n * fact(n-1);
}
n=3
fact(3)
environment
n=2
environment
n=1
environment
n=0
environment
static int fact(int n) {
if (n == 0) return 1;
else return n * fact(n-1);
}
fact(2)
static int fact(int n) {
if (n == 0) return 1;
else return n * fact(n-1);
}
fact(1)
static int fact(int n) {
if (n == 0) return 1;
else return n * fact(n-1);
}
1
fact(0)
static int fact(int n) {
if (n == 0) return 1;
else return n * fact(n-1);
}
n=3
fact(3)
environment
n=2
environment
n=1
environment
static int fact(int n) {
if (n == 0) return 1;
else return n * fact(n-1);
}
fact(2)
static int fact(int n) {
if (n == 0) return 1;
else return n * fact(n-1);
}
fact(1)
static int fact(int n) {
if (n == 0) return 1;
else return n * fact(n-1);
}
1
1
n=3
fact(3)
environment
n=2
environment
n=1
environment
static int fact(int n) {
if (n == 0) return 1;
else return n * fact(n-1);
}
fact(2)
static int fact(int n) {
if (n == 0) return 1;
else return n * fact(n-1);
}
1
fact(1)
static int fact(int n) {
if (n == 0) return 1;
else return n * fact(n-1);
}
1
1
n=3
environment
n=2
environment
fact(3)
static int fact(int n) {
if (n == 0) return 1;
else return n * fact(n-1);
}
fact(2)
static int fact(int n) {
if (n == 0) return 1;
else return n * fact(n-1);
}
1
2
n=3
environment
n=2
environment
fact(3)
static int fact(int n) {
if (n == 0) return 1;
else return n * fact(n-1);
}
2
fact(2)
static int fact(int n) {
if (n == 0) return 1;
else return n * fact(n-1);
}
1
2
n=3
environment
fact(3)
static int fact(int n) {
if (n == 0) return 1;
else return n * fact(n-1);
}
3
2
n=3
fact(3)
environment
static int fact(int n) {
if (n == 0) return 1;
else return n * fact(n-1);
}
3
2
public class Factorial {
public static int fact(int n) {
if (n == 0) return 1;
else return n * fact(n-1);
}
}
public static void main(String[] args) {
System.out.println(fact(3));
}
6
% java Factorial
6