Added Heap's Algorithm

Generates permutations of given numbers

Author: sulphatet

generate_permutations.py

@@ -0,0 +1,16 @@
+def generate(A,k):
+    if k ==1:
+        print(A)
+        return
+    else:
+        for i in range(k):
+            generate(A,k-1)
+            if(i<k-1):
+                if k%2 == 0:
+                    A[i],A[k-1] = A[k-1],A[i]
+                else:
+                    A[0],A[k-1] = A[k-1],A[0]
+
+A = [1,2,3,4] #test-case
+x = len(A)
+generate(A,x)