Create quicksort.py

BubbaBeans · web-flow · commit a7c77faa3bc6 · 2019-10-01T14:24:43.000-07:00
Quick and dirty implementation of a quicksort algorithm
diff --git a/allalgorithms/sorting/quicksort.py b/allalgorithms/sorting/quicksort.py
@@ -0,0 +1,21 @@
+def partition(xs, start, end):
+    follower = leader = start
+    while leader < end:
+        if xs[leader] <= xs[end]:
+            xs[follower], xs[leader] = xs[leader], xs[follower]
+            follower += 1
+        leader += 1
+    xs[follower], xs[end] = xs[end], xs[follower]
+    return follower
+
+def _quicksort(xs, start, end):
+    if start >= end:
+        return
+    p = partition(xs, start, end)
+    _quicksort(xs, start, p-1)
+    _quicksort(xs, p+1, end)
+    
+def quicksort(xs):
+    _quicksort(xs, 0, len(xs)-1)
+
+# To use: create a list and send it to quicksort:  quicksort(list placed here)
