History of Idiom 19 > diff from v16 to v17

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Version 16

2015-09-04, 09:08:04

Version 17

2015-10-29, 14:05:12

Idiom #19 Reverse a list

Reverse the order of the elements of list x .
This may reverse "in-place" and destroy the original ordering.

Idiom #19 Reverse a list

Reverse the order of the elements of list x .
This may reverse "in-place" and destroy the original ordering.

Clojure

Clojure

Code

(reverse x)

Code

(reverse x)

Doc URL

http://clojuredocs.org/clojure.core/reverse

Doc URL

http://clojuredocs.org/clojure.core/reverse

Imports

import std.range;

Imports

import std.range;

Code

auto y = x.retro;

Code

auto y = x.retro;

Comments bubble

This doesn't allocate a new list or modify the original, but creates an iterator that traverses the list in reverse order.

Comments bubble

This doesn't allocate a new list or modify the original, but creates an iterator that traverses the list in reverse order.

Demo URL

http://dpaste.dzfl.pl/ebf4256b37c4

Demo URL

http://dpaste.dzfl.pl/ebf4256b37c4

Code

for i, j := 0, len(x)-1; i < j; i, j = i+1, j-1 {
	x[i], x[j] = x[j], x[i]
}

Code

for i, j := 0, len(x)-1; i < j; i, j = i+1, j-1 {
	x[i], x[j] = x[j], x[i]
}

Comments bubble

This loop reverts "in-place" (in the original list, not creating a new one).

Comments bubble

This loop reverts "in-place" (in the original list, not creating a new one).

Origin

http://stackoverflow.com/a/19239850/871134

Origin

http://stackoverflow.com/a/19239850/871134

Demo URL

http://play.golang.org/p/vkJg_D1yUb

Demo URL

http://play.golang.org/p/vkJg_D1yUb

Imports

import std.algorithm;

Imports

import std.algorithm;

Code

reverse(x);

Code

reverse(x);

Comments bubble

Reverses x in-place.

Comments bubble

Reverses x in-place.

Doc URL

http://dlang.org/phobos/std_algorithm.html#reverse

Doc URL

http://dlang.org/phobos/std_algorithm.html#reverse

Java

Java

Imports

import java.util.List;

Imports

import java.util.List;

Code

static <T> void reverse(List<T> x){
	int n = x.size();
	for(int i=0;i<n/2;i++){
		T tmp = x.get(i);
		x.set(i, x.get(n-i-1));
		x.set(n-i-1, tmp);
	}
}

Code

static <T> void reverse(List<T> x){
	int n = x.size();
	for(int i=0;i<n/2;i++){
		T tmp = x.get(i);
		x.set(i, x.get(n-i-1));
		x.set(n-i-1, tmp);
	}
}

Comments bubble

This method works for lists of any element type T .

In case of an odd number of elements, the central element doesn't need to be swapped.

Comments bubble

This method works for lists of any element type T .

In case of an odd number of elements, the central element doesn't need to be swapped.

Demo URL

http://ideone.com/kxgipq

Demo URL

http://ideone.com/kxgipq

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History of Idiom 19 > diff from v16 to v17

Version 16

Version 17

Idiom #19 Reverse a list

Idiom #19 Reverse a list

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