Refactor random-choice

Prefer initializing `result` to an empty array of size `m`, which makes the
algorithm a bit more elegant.

1 files changed, 2 insertions, 2 deletions

diff --git a/scratch/facebook/hard/random-choice.py b/scratch/facebook/hard/random-choice.py
index 95029ceb80a4..95e834a2eb01 100644
--- a/scratch/facebook/hard/random-choice.py
+++ b/scratch/facebook/hard/random-choice.py
@@ -6,8 +6,8 @@ def choose_a(m, xs):
     Randomly choose `m` elements from `xs`.
     This algorithm runs in linear time with respect to the size of `xs`.
     """
-    result = xs[:m]
-    for i in range(m, len(xs)):
+    result = [None] * m
+    for i in range(len(xs)):
         j = random.randint(0, i)
         if j < m:
             result[j] = xs[i]