D. J.:

- Added the leetcode problem and solution for 204

Author: nobodyPerfecZ

README.md

@@ -190,6 +190,7 @@
 - [200 Number of Islands](https://leetcode.com/problems/number-of-islands/description/)
 - [201 Bitwise AND of Numbers Range](https://leetcode.com/problems/bitwise-and-of-numbers-range/description/)
 - [202 Happy Number](https://leetcode.com/problems/happy-number/description/)
+- [204 Count Primes](https://leetcode.com/problems/count-primes/description/)
 - [205 Isomorphic Strings](https://leetcode.com/problems/isomorphic-strings/description/)
 - [207 Course Schedule](https://leetcode.com/problems/course-schedule/description/)
 - [208 Implement Trie (Prefix Tree)](https://leetcode.com/problems/implement-trie-prefix-tree/description/)

awesome_python_leetcode/_204_count_primes.py

@@ -0,0 +1,21 @@
+class Solution:
+    """Base class for all LeetCode Problems."""
+
+    def countPrimes(self, n: int) -> int:
+        """
+        Given an integer n, return the number of prime numbers that are strictly less
+        than n.
+        """
+        # Time Complexity: O(n*sqrt(n))
+        # Space Complexity: O(n)
+        if n == 0 or n == 1:
+            return 0
+        primes = [True for i in range(n)]
+        primes[0] = primes[1] = False
+        p = 2
+        while p * p < n:
+            if primes[p]:
+                for i in range(p * p, n, p):
+                    primes[i] = False
+            p += 1
+        return sum(primes)

tests/test_204_count_primes.py

@@ -0,0 +1,17 @@
+import pytest
+
+from awesome_python_leetcode._204_count_primes import Solution
+
+
+@pytest.mark.parametrize(
+    argnames=["n", "expected"],
+    argvalues=[
+        (10, 4),
+        (0, 0),
+        (1, 0),
+    ],
+)
+def test_func(n: int, expected: int):
+    """Tests the solution of a LeetCode problem."""
+    primes = Solution().countPrimes(n)
+    assert primes == expected