Initial solution to homework

qselect.py

@@ -0,0 +1,15 @@
+import random
+
+def qselect(i, xs):
+    if xs == []: return None
+
+    pivot = xs.pop(random.randrange(len(xs)))
+    left = [x for x in xs if x < pivot]
+    right = [x for x in xs if x >= pivot]
+
+    if i > len(left):
+        return qselect(i - len(left) - 1, right)
+    elif i == len(left):
+        return pivot
+    else:
+        return qselect(i, left)