The Next Generation of 2D Roleplaying Games
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//
// fib.java
// fib
//
// Created by avansc on 7/29/09.
// Copyright (c) 2009 BrOkEnBiT. All rights reserved.
//
import java.util.*;
import java.util.StringTokenizer;
public class fib {
static public int pass(String data)
{
StringTokenizer st = new StringTokenizer(data,"+");
while(st.hasMoreTokens())
{
if(Integer.parseInt(st.nextToken()) > 2)
return 0;
}
return 1;
}
static public String split(String data)
{
StringTokenizer st = new StringTokenizer(data,"+");
String temp = "";
String ret = "";
int a = 0;
int b = 0;
while(st.hasMoreTokens())
{
temp = st.nextToken();
if(Integer.parseInt(temp) < 3)
{
ret += temp + "+";
}else{
a = Integer.parseInt(temp)-2;
b = Integer.parseInt(temp)-1;
ret += a+"+"+b+"+";
}
}
return ret.substring(0, ret.length()-1);
}
public static void main (String args[])
{
String fib = "8";
System.out.println(fib);
while(pass(fib) != 1)
{
fib = split(fib);
System.out.println(fib);
}
StringTokenizer st = new StringTokenizer(fib,"+");
System.out.println(st.countTokens());
}
}
That I do not understand. I don't know java. Barley c++ aparently lol. I understand how the series works, but not the code if that makes sense.avansc wrote:okay so here is a java program that might help a little.
output.Code: Select all
// // fib.java // fib // // Created by avansc on 7/29/09. // Copyright (c) 2009 BrOkEnBiT. All rights reserved. // import java.util.*; import java.util.StringTokenizer; public class fib { static public int pass(String data) { StringTokenizer st = new StringTokenizer(data,"+"); while(st.hasMoreTokens()) { if(Integer.parseInt(st.nextToken()) > 2) return 0; } return 1; } static public String split(String data) { StringTokenizer st = new StringTokenizer(data,"+"); String temp = ""; String ret = ""; int a = 0; int b = 0; while(st.hasMoreTokens()) { temp = st.nextToken(); if(Integer.parseInt(temp) < 3) { ret += temp + "+"; }else{ a = Integer.parseInt(temp)-2; b = Integer.parseInt(temp)-1; ret += a+"+"+b+"+"; } } return ret.substring(0, ret.length()-1); } public static void main (String args[]) { String fib = "8"; System.out.println(fib); while(pass(fib) != 1) { fib = split(fib); System.out.println(fib); } StringTokenizer st = new StringTokenizer(fib,"+"); System.out.println(st.countTokens()); } }
8
6+7
4+5+5+6
2+3+3+4+3+4+4+5
2+1+2+1+2+2+3+1+2+2+3+2+3+3+4
2+1+2+1+2+2+1+2+1+2+2+1+2+2+1+2+1+2+2+3
2+1+2+1+2+2+1+2+1+2+2+1+2+2+1+2+1+2+2+1+2
21
so thats what happens to fib(8) and 1 and 2 are equal to 1. so you just count the terms. and fib(8) = 21
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cout << "Processing fib)" << n << ")...";
if (n < 3)
{
cout << "Return 1!\n";
return(1);
}
else
{
cout << "Call fib(" << n-2 << ") and fib(" << n-1 << ").\n";
return( fib(n-2) + fib(n-1));
ok it makes sense that it will always return 1 if n < 2 because the first 2 numbers are 1. But what had me was it subtracts 2 and 1 so essentially 3, why doesn't it turn out negative?avansc wrote:okay different approach..
fib(n) will always return 1 unless n > 2. and if n greater than 2 it subtracts 2 and 1 and calls it self with those values.
everytime fib(n) is called. the return 1 will be called. and since its + it just adds the number of times fib was called.
What you refer to as "blank", mathmeticians refer to as "n" (or "x" or whatever letter or symbol they please really, it's similar to how you can name your variables in C++ whatever you'd like). See Below.jtst1 wrote:The blank was for a number any number. How does it know that 8 is the 6th number in the fib series? or 10 is some other number in the series.
In algebra we often replace an unknown value with a variable (often in the form of a letter, "n" in this case).jtst1 wrote:I would like to understand what the code does, like the n-2+n-1 I don't understand what n is, and F
No, it does not subtract three.jtst1 wrote:ok it makes sense that it will always return 1 if n < 2 because the first 2 numbers are 1. But what had me was it subtracts 2 and 1 so essentially 3, why doesn't it turn out negative?
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#include <iostream>
#include <vector>
using namespace std;
int main() {
int f = 0, g = 1;
for (int i = 2; i <= 40; i++) {
f = f + g;
g = f - g;
printf("f%d = %d\n", i, f);
}
return 0;
}Code: Select all
fib(0) = 1
fib(1) = 1
fib(n) = (n - 2) + (n - 1) for n > 1Code: Select all
Now, fib(n) = fib(n - 2) + fib(n - 1)
Then fib(2) = fib(2 - 2) + fib(2 - 1)
So fib(2) = fib(0) + fib(1)
fib(2) = 1 + 1, since fib(0) = 1 and fib(1) = 1Code: Select all
fib(4)
/ \
fib(2) + fib(3)
/ \ / \
fib(0) + fib(1) fib(1) + fib(2)
| | | / \
1 1 1 fib(0) + fib(1)
| |
1 1
The fourth Fibonacci number is 3.wtetzner wrote:Actually I just though of a visual way to show how it works. Since fib calls two instances of itself, it creates a tree of function calls.Hopefully that helps make things more clear.Code: Select all
fib(4) / \ fib(2) + fib(3) / \ / \ fib(0) + fib(1) fib(1) + fib(2) | | | / \ 1 1 1 fib(0) + fib(1) | | 1 1