Added pancake sorting

Author: FreeTymeKiyan

Other/PancakeSorting.java

@@ -0,0 +1,52 @@
+/**
+ * Given an an unsorted array, sort the given array.
+ * You are allowed to do only following operation on array
+ * flip(arr, i): Reverse array from 0 to i
+ * 
+ * Tags: Sort
+ */
+class PancakeSorting {
+    public static void main(String[] args) {
+        PancakeSorting p = new PancakeSorting();
+        int[] A = {23, 10, 20, 11, 12, 6, 7};
+        p.pancakeSort(A);
+        for (int n : A) System.out.print(n + ", ");
+    }
+    
+    /**
+     * Find max from from start to end
+     * If max is not at the end, filp it to first and flip it to end
+     * Reduce array size by one 
+     * Stop till size reduced to 1
+     */
+    public void pancakeSort(int[] A) {
+        if (A == null || A.length <= 1) return;
+        
+        for (int i = A.length; i > 1; i--) { // i is current size
+            int mi = findMax(A, i);
+            if (mi != i) {
+                flip(A, mi);
+                flip(A, i - 1);
+            }
+        }
+    }
+    
+    private void flip(int[] A, int i) {
+        int temp, start = 0;
+        while (start < i) {
+            temp = A[start];
+            A[start] = A[i];
+            A[i] = temp;
+            start++;
+            i--;
+        }
+    }
+    
+    private int findMax(int[] A, int size) {
+        int mi = 0;
+        for (int i = 0; i < size; i++) {
+            if (A[i] > A[mi]) mi = i;
+        }
+        return mi;
+    }
+}