Add pancake sort (#344)

Add Pancake Sort

README.md

@@ -63,6 +63,7 @@ C
 	- InsertionSort
 	- MergeSort
 	- OtherBubbleSort
+	- PancakeSort
 	- QuickSort
 	- SelectionSort
 	- ShakerSort

sorting/PancakeSort.c

@@ -0,0 +1,78 @@
+// Sorting of array list using pancake sort
+#include <stdlib.h>
+#include <stdio.h>
+
+/* Reverses the array */
+void flip(int arr[], int i)
+{
+    int temp, start = 0;
+
+    while (start < i)
+    {
+        temp = arr[start];
+        arr[start] = arr[i];
+        arr[i] = temp;
+        start++;
+        i--;
+    }
+}
+
+// Returns index of the maximum element in arr[0..n-1]
+int findMax(int arr[], int n)
+{
+    int maxElementIdx, i;
+
+    for (maxElementIdx = 0, i = 0; i < n; ++i)
+        if (arr[i] > arr[maxElementIdx])
+                maxElementIdx = i;
+
+    return maxElementIdx;
+}
+
+// Sorts the array using flip operations
+int pancakeSort(int *arr, int n)
+{
+    // Start from the complete array and one by one reduce current size by one
+    for (int curr_size = n; curr_size > 1; --curr_size)
+    {
+        // Find index of the maximum element in arr[0..curr_size-1]
+        int maxElementIdx = findMax(arr, curr_size);
+
+        // Move the maximum element to end of current array if it's not already at the end
+        if (maxElementIdx != curr_size-1)
+        { 
+            // To move at the end, first move maximum number to beginning
+            flip(arr, maxElementIdx); 
+
+            // Now move the maximum number to end by reversing current array
+            flip(arr, curr_size-1); 
+        }
+    }
+}
+
+// Displays the array, passed to this method
+void display(int arr[], int n)
+{
+    for(int i = 0; i < n; i++)
+    {
+        printf("%d ", arr[i]);
+    }
+
+    printf("\n");
+} 
+
+// Driver program to test above function
+int main()
+{ 
+    int arr[] = {23, 10, 20, 11, 12, 6, 7};
+    int n = sizeof(arr)/sizeof(arr[0]); 
+
+    printf("Original array: ");
+    display(arr, n);
+
+    pancakeSort(arr, n);
+    printf("Sorted array: ");
+    display(arr, n);
+
+    return 0;
+}