Python 实现：计算 1 到 10⁷ 以内素数个数（含代码与示例）

```python def count_primes(n): if n < 2: return 0 is_prime = [True] * (n + 1) is_prime[0] = is_prime[1] = False for i in range(2, int(n 0.5) + 1): if is_prime[i]: for j in range(i * i, n + 1, i): is_prime[j] = False return sum(is_prime) n = int(input()) print(count_primes(n)) ``` ######[AI问答 | 118点数解答 | 2026-01-11 17:36:06]