Insertion_sort.md

Insertion Sort - O[n²]

The array is virtually split into a sorted and an unsorted part.
Values from the unsorted part are picked and placed at the correct position in the sorted part.

Cpp

using namespace std; 
  
/* Function to sort an array using insertion sort*/
void insertionSort(int arr[], int n)  
{  
    int i, key, j;  
    for (i = 1; i < n; i++) 
    {  
        key = arr[i];  
        j = i - 1;  
  
        /* Move elements of arr[0..i-1], that are  
        greater than key, to one position ahead  
        of their current position */
        while (j >= 0 && arr[j] > key) 
        {  
            arr[j + 1] = arr[j];  
            j = j - 1;  
        }  
        arr[j + 1] = key;  
    }  
}  
  
// A utility function to print an array of size n  
void printArray(int arr[], int n)  
{  
    int i;  
    for (i = 0; i < n; i++)  
        cout << arr[i] << " ";  
    cout << endl; 
}  
  
/* Driver code */
int main()  
{  
    int arr[] = { 12, 11, 13, 5, 6 };  
    int n = sizeof(arr) / sizeof(arr[0]);  
  
    insertionSort(arr, n);  
    printArray(arr, n);  
  
    return 0;  
}

Python

def insertionSort(arr): 
  
    # Traverse through 1 to len(arr) 
    for i in range(1, len(arr)): 
  
        key = arr[i] 
  
        # Move elements of arr[0..i-1], that are 
        # greater than key, to one position ahead 
        # of their current position 
        j = i-1
        while j >= 0 and key < arr[j] : 
                arr[j + 1] = arr[j] 
                j -= 1
        arr[j + 1] = key 
  
  
# Driver code to test above 
arr = [12, 11, 13, 5, 6] 
insertionSort(arr) 
for i in range(len(arr)): 
    print ("% d" % arr[i])