leetcode: Add 0204

src/leetcode/0204.count-primes/Cargo.toml

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+[package]
+name = "lc-0204-count-primes"
+version = "0.1.0"
+edition = "2021"
+publish = false
+
+[dependencies]

src/leetcode/0204.count-primes/index.md

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+
+# 
+
+[问题描述](../problems/)

src/leetcode/0204.count-primes/src/main.rs

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+// Copyright (c) 2024 Xu Shaohua <[email protected]>. All rights reserved.
+// Use of this source is governed by General Public License that can be found
+// in the LICENSE file.
+
+// Enumeration
+// 筛选法求质数
+pub fn count_primes1(n: i32) -> i32 {
+    debug_assert!((0..=500_000).contains(&n));
+
+    if n <= 1 {
+        return 0;
+    }
+
+    let n = n as usize;
+    let mut primes: Vec<bool> = vec![true; n + 1];
+
+    //平方根
+    let mut prime_count: i32 = 0;
+    for i in 2..n {
+        // 如果这个数值是和数, 就直接跳过它.
+        if !primes[i] {
+            continue;
+        }
+        prime_count += 1;
+
+        let mut pos = i;
+        while pos < n {
+            primes[pos] = false;
+            pos += i;
+        }
+    }
+
+    prime_count
+}
+
+pub type SolutionFn = fn(i32) -> i32;
+
+fn check_solution(func: SolutionFn) {
+    assert_eq!(func(10), 4);
+    assert_eq!(func(0), 0);
+    assert_eq!(func(1), 0);
+    assert_eq!(func(2), 0);
+    assert_eq!(func(3), 1);
+}
+
+fn main() {
+    check_solution(count_primes1);
+}
+
+#[cfg(test)]
+mod tests {
+    use super::{check_solution, count_primes1};
+
+    #[test]
+    fn test_count_primes1() {
+        check_solution(count_primes1);
+    }
+}