feat: find_missing

tests/test_essentials.py

@@ -16,4 +16,12 @@ def test_subarray_sum():
 	expected = [25, [5,4,1,7,8]]
 	assert result == expected
 
-
+def test_find_missing():
+	input = [8,2,4,5,3,7,1]
+	result = find_missing(input)
+	expected = 6
+	assert result == expected
+	input = [1,2,3,5]
+	result = find_missing(input)
+	expected = 4
+	assert result == expected