# Difference between revisions of "Insertion sort"

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Insertion sort is similar to bubble sort, but is more efficient as it reduces element comparisons somewhat with each pass. An element is compared to all the prior elements until a lesser element is found. In other words, if an element contains a value less than all the previous elements, it compares the element to all the previous elements before going on to the next comparison. Although this algorithm is more efficient than the Bubble sort, it is still inefficient compared to many other sort algorithms since it, and bubble sort, move elements only one position at a time. However, insertion sort is a good choice for small lists (about 30 elements or fewer), and for nearly-sorted lists.

## Implementations

### C++

```#include <vector>
using namespace std;

template<typename T>

void sortieren(void)
{
int k = 0;
T x ;
for(unsigned int j = 0; j < m_array.size(); j++){
x = m_array.at(j);
k = j;

while(k > 0 && x > m_array.at(k-1)){

m_array.erase(m_array.begin() +k);
m_array.insert(m_array.begin()+k,m_array.at(k-1));
k --;
}
m_array.erase(m_array.begin() +k);
m_array.insert(m_array.begin()+k,x);
}
}
```

### C

``` void insertSort(int a[], size_t length) {
int i, j, value;

for(i = 1; i < length; i++) {
value = a[i];
for (j = i - 1; j >= 0 && a[j] > value; j--) {
a[j + 1] = a[j];
}
a[j + 1] = value;
}
}
```

### C#

```static void InsertSort(IComparable[] array)
{
int i, j;

for (i = 1; i < array.Length; i++)
{
IComparable value = array[i];
j = i - 1;
while ((j >= 0) && (array[j].CompareTo(value) > 0))
{
array[j + 1] = array[j];
j--;
}
array[j + 1] = value;
}
}
```

### C# 2.0

This example sorts a list of objects of any type T that implements IComparable. It demonstrates C# 2.0 generics and in particular the "where" clause.

```static void InsertSort<T>(IList<T> list) where T : IComparable<T>
{
int i, j;

for (i = 1; i < list.Count; i++)
{
T value = list[i];
j = i - 1;
while ((j >= 0) && (list[j].CompareTo(value) > 0))
{
list[j + 1] = list[j];
j--;
}
list[j + 1] = value;
}
}
```

### Pascal

```PROCEDURE InsertionSort(var Menge: MengeIntegerTyp; Links, Rechts: INTEGER;)
VAR
Index, Einfuegeposition, Zwischenspeicher: INTEGER;
BEGIN
FOR Index := Links + 1 TO Rechts DO
BEGIN
Zwischenspeicher := Menge[Index];
Einfuegeposition := Index;
WHILE ((Menge[Einfugeposition - 1] > Zwischenspeicher) AND
BEGIN
Menge[Einfuegeposition] := Menge[Einfuegeposition - 1];
Einfuegeposition := Einfuegeposition - 1;
END;
Menge[Einfuegeposition] := Zwischenspeicher;
END;
END;
```

### OCaml

```# let rec sort = function
| [] -> []
| h1::t as list -> match sort t with
| h2::t when h1>h2 -> h2::sort(h1::t)
| t' -> if t==t' then list else h1::t';;
val sort : 'a list -> 'a list = <fun>
```

For example:

```# sort [1;9;2;8;3;7;4;6;5];;
- : int list = [1; 2; 3; 4; 5; 6; 7; 8; 9]
```

### CAML

```let rec insertion_Sort l =
match l with
| [] -> []
| (h::n) -> insert h (insertion_Sort n)
and insert t l =
match l with
| [] -> [t]
| (h::n) -> if t > h then h::(insert t n)
else t::h::n ;;
```

### Common Lisp

```(defun insert (target list)
(if (equal list NIL)
(cons target '())
(if (<= target (first list))
(cons target list)
(cons (first list) (insert target (rest list))))))
(defun insertSort(myList)
(if (NULL mylist)
'()
(insert (first myList) (insertSort (rest myList)))))
```

### F#

``` let rec insert x l =  match l with
| []    -> [x]
| y::ys -> if x <= y then x::y::ys
else y::insert x ys
and insertsort l = match l with
| []    -> []
| x::xs -> insert x (insertsort xs)
```

### Java

```public static void insertionSort(int data[])
{
for (int i = 0; i < data.length; i++)
{
int temp = data[i];
int j = i - 1;

while (j >= 0 && temp < data[j])
{
data[j + 1] = data[j];
data[j] = temp;

j--;
}
}
}
```

#### Java Alt

```   static void insertionSort (int[] A) {
int j;
for (int i = 1; i < A.length; i++) {
int a = A[i];
for (j = i - 1; j >=0 && A[j] > a; j--)
A[j + 1] = A[j];
A[j + 1] = a;
}
}
```

``` insert :: Ord a => a -> [a] -> [a]
insert item []  = [item]
insert item (h:t) | item <= h = item:h:t
| otherwise = h:(insert item t)

insertsort :: Ord a => [a] -> [a]
insertsort []    = []
insertsort (h:t) = insert h (insertsort t)
```

#### Shorter alt

The insert function is the same as above.

``` insert :: Ord a => a -> [a] -> [a]
insert item []  = [item]
insert item (h:t) | item <= h = item:h:t
| otherwise = h:(insert item t)

insertsort :: Ord a => [a] -> [a]
insertsort  =  foldr insert []
```

#### Alt

```insertionSort :: (Ord a) => [a] -> OrdList a
insertionSort [] =[]
insertionSort (a:as) = insert a (insertionSort as)

insert :: (Ord a) => a -> OrdList a -> OrdList a
insert a1 [] = [a1]
insert a1 (a2:as)
| a1 <= a2 = a1:a2:as
| otherwise = a2:insert a1 as
```

### Perl

``` sub insert_sort {
for(my \$i = 0; \$i <= \$#_; \$i++) {
my (\$j, \$val) = (\$i - 1, \$_[\$i]);
\$_[\$j-- + 1] = \$_[\$j] while (\$j >= 0 && \$_[\$j] > \$val);
\$_[\$j+1] = \$val;
}
}
```

### PHP

```for(\$j=1; \$j < count(\$array); \$j++){
\$temp = \$array[\$j];
\$i = \$j;
while((\$i >= 0) && (\$array[\$i-1] > \$temp)){
\$array[\$i] = \$array[\$i-1];
\$i--;
}
\$array[\$i] = \$temp;
}
```

### Python

```def insertsort(array):
for removed_index in range(1, len(array)):
removed_value = array[removed_index]
insert_index = removed_index
while insert_index > 0 and array[insert_index - 1] > removed_value:
array[insert_index] = array[insert_index - 1]
insert_index = insert_index - 1
array[insert_index] = removed_value
```

### Standard ML

```fun insertsort [] = []
| insertsort (x::xs) =
let fun insert (x:real, []) = [x]
| insert (x:real, y::ys) =
if x<=y then x::y::ys
else y::insert(x, ys)
in insert(x, insertsort xs)
end;
```

### Turing

```var nombres, limit : int
get nombres
get limit
var sure : boolean := false
var g, smaller : int := 0
var k : int := limit + 1
var last : int := limit
var first : int := 1
var last2 : int := nombres
var br : int := limit - 1
var rann, sort : array 1 .. nombres of int
for i : 1 .. nombres
rann (i) := Rand.Int (0, limit)
sort (i) := k
end for
if rann (1) <= limit then
last := rann (1)
sort (1) := rann (1)
end if
for h : 2 .. upper (rann)
if rann (h) < last then
for decreasing f : nombres - 1 .. 1
sort (f + 1) := sort (f)
end for
sort (1) := rann (h)
last := rann (h)
else
for i : 1 .. upper (rann)
if rann (h) < sort (i) then
for decreasing f : nombres - 1 .. i
sort (f + 1) := sort (f)
end for
sort (i) := rann (h)
exit
end if
end for
end if
end for
for b : 1 .. upper (sort)
put " ", sort (b) ..
end for
```