Solve "Move Zeroes to End"

Write a function to modify an array of integers in-place such that all of the
zeroes in the array are at the end, and the order of the other integers is not
changed.

scratch/facebook/move-zeroes-to-end.py

@@ -0,0 +1,26 @@
+def move_zeroes_to_end(xs):
+    n_zeroes = 0
+    for x in xs:
+        if x == 0:
+            n_zeroes += 1
+
+    i = 0
+    while i < len(xs) - 1:
+        if xs[i] == 0:
+            j = i + 1
+            while j < len(xs) and xs[j] == 0:
+                j += 1
+            if j >= len(xs):
+                break
+            xs[i], xs[j] = xs[j], xs[i]
+        i += 1
+    # add zeroes to the end
+    for i in range(n_zeroes):
+        xs[len(xs) - 1 - i] = 0
+
+xs = [1, 2, 0, 3, 4, 0, 0, 5, 0]
+print(xs)
+move_zeroes_to_end(xs)
+assert xs == [1, 2, 3, 4, 5, 0, 0, 0, 0]
+print(xs)
+print("Success!")