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insertion-sort.md

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+# Insertion Sort
+
+Insertion sort is a comparision based sorting. In this sorting technique, we maintain a sub-list which is always sorted and then we take one element from the list and insert it at its correct place. We does so till all elements are inserted into sublist. For example, while playing cards we sort cards in our hand. Starting from left and moving to right,we keep on inserting the card at it's right place till end.
+
+## Example
+
+![alt tag](https://cloud.githubusercontent.com/assets/13117482/15633518/04ca4468-25cc-11e6-96af-feb395b456e0.png)
+
+In the above example, Grey Shaded sublist is always sorted and in each step we are inserting leftmost element of white sublist at it's correct position. Hence, we have sorted the complete list in this way.
+
+## Algorithm
+
+Loop for i=0 to N-1:
+* Pick element array[i] and insert it into sorted sublist array[0...i-1]
+
+## Complexity
+
+```
+Space complexity: O(1)      // Auxillary/temporary space is used.
+
+Time complexity: O(n*n)     // Two nested for loops are used.
+```
+
+## Cpp Implementation
+
+```cpp
+// 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; // place element key at it's correct place
+   }
+}
+
+int main()
+{
+    // array to be sorted
+    int arr[5] = {12, 11, 13, 5, 6};
+
+    // call the insertion sort
+    insertionSort(arr, 5);
+
+    // prints sorted array i.e. 5 6 11 12 13
+    for(int i=0; i<5; i++)
+        std::cout << arr[i] << " ";
+    return 0;
+}
+```
+
+:rocket: [Run Code](https://repl.it/CWZq)
+
+## Python Implementation
+
+```python
+# Function to perform insertion sort
+def insertionSort(arr):
+    # Traverse through array
+    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 # place element key at it's correct place
+
+# array to be sorted
+arr = [12, 11, 13, 5, 6]
+# call the insertion sort
+insertionSort(arr)
+# prints sorted array i.e. 5 6 11 12 13
+for i in range(len(arr)):
+    print(arr[i],end = ' ')
+```
+
+:rocket: [Run Code](https://repl.it/CWZi)
+
+## Advantages
+
+1. Efficient for small set of data and data set that are almost sorted.
+2. Simply implemented.
+3. Mostly better than bubble sort and selection sort & generally used with merge sort.
+
+## Disadvantages
+
+1. It's less efficient on large set of data.
+2. Less effecient than merge sort, heap sort and quick sort.