29 replies to this topic

[REvolution]

So.... Is everyone using C#??

I recognize that <studio.h> header

um, No. most of it is in C

and it's <stdio.h> the Standard C library I/O functions,

void swap(int* a,int* {

*b=*b+*a;
*a=*b-*a;
*b=*b-*a;

}

[SigFLUP]

SigFlup, Could you explain how yours works. I'm curious to know what's happening there.

oh sorry, I didn't really answer that. If you xor something by a number and xor it again you get the same number... so it's kinda like hiding a number inside another number. So we xor one number into another and the other into the first one. Rinse and repeat and you just swapped them.

[z3ros3c]

Here's my implementation in Python. I'm kind of surprised nobody did this... It doesn't seem to break the rules at all.

Spoiler

def swap(a,b):
  return (b,a)

(a,b) = swap(a,b)

Granted, it's not as cool as doing the XOR trick, but it's a lot shorter code than anyone else has written.

You can also shorten it even further, like so:

Spoiler

swap = lambda (a,b): (b,a)
(a,b) = swap((a,b))

Edited by z3ros3c, 18 May 2010 - 12:36 AM.

[Lord Wud]

Here's my answer with python. I looked around at some other peoples, and I feel like I'm missing something huge though. If I am could someone care to explain?

Spoiler

def swapab(a,b):
  a = a + b
  b = a - b
  a = a - b 
  return a,b

Edited by Lord Wud, 13 September 2010 - 09:52 AM.

[codered22]

This is quite fun. ;)

Spoiler

// File: main.cpp
// Title: BinRev BASIC001
// Description: Using the language of your choice: Write a function in which
//          	two integer variables (a and b) have their values swapped
//          	without using any temporary variables.
// Author: codered22
// Date: 2010-10-23

#include<iostream>

using namespace std;

void swapValues(int & _a, int & _b) {
	_a += _b;
	_b = _a - _b;
	_a = _a - _b;
}

int main() {
	int a, b;

	cin >> a >> b;
	
	swapValues(a, b);
	
	cout << a << " " << b;
	
	return 0;
}

[heisenbug]

Once again Perl is awesome.

Spoiler

($a,$b) = ($b,$a);

[pix6ie]

In python:

a = 10
b = 20
a = a*2
b = a/2

Is this too simplified??

[rainwater_stillicide]

In python:

a = 10
b = 20
a = a*2
b = a/2

Is this too simplified??

It's not too simplified (it does take two variables and swap them) but it doesn't do it in a general way, it will only work for certain numbers (i.e., where b = 2a).

Try and come up with a solution which can work for an arbitrary pair of numbers.

[heisenbug]

In python:

a = 10
b = 20
a = a*2
b = a/2

Is this too simplified??

It's not too simplified (it does take two variables and swap them) but it doesn't do it in a general way, it will only work for certain numbers (i.e., where b = 2a).

Try and come up with a solution which can work for an arbitrary pair of numbers.

It is just too easy to do in Python. Don't make it too hard on yourself. Here is the easiest way to do it in Python.

Spoiler

a,b=b,a

[s0urd]

Old thread but...

a = 2
b = 3
print a, b
a, b = b, a
print a, b