lc: Add number of 1 bits

leetcode/191.number_of_1_bits/Cargo.toml

@@ -0,0 +1,7 @@
+[package]
+name = "lc_191_number_of_1_bits"
+version = "0.1.0"
+edition = "2021"
+publish = false
+
+[dependencies]

leetcode/191.number_of_1_bits/src/main.rs

@@ -0,0 +1,62 @@
+// Copyright (c) 2023 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.
+
+//! Problem: [Number of 1 bits](https://leetcode.com/problems/number-of-1-bits)
+
+fn solution1(n: u32) -> i32 {
+    let mut n = n;
+    let mut count = 0;
+    while n != 0 {
+        count += n % 2;
+        n /= 2;
+    }
+    count as i32
+}
+
+fn solution2(n: u32) -> i32 {
+    n.count_ones() as i32
+}
+
+fn main() {
+    let n = 0b00000000000000000000000000001011;
+    assert_eq!(solution1(n), 3);
+
+    let n = 0b00000000000000000000000010000000;
+    assert_eq!(solution1(n), 1);
+
+    let n = 0b11111111111111111111111111111101;
+    assert_eq!(solution1(n), 31);
+
+    let n = 0b11111111111111111111111111111101;
+    assert_eq!(solution2(n), 31);
+}
+
+#[cfg(test)]
+mod tests {
+    use super::{solution1, solution2};
+
+    #[test]
+    fn test_solution1() {
+        let n = 0b00000000000000000000000000001011;
+        assert_eq!(solution1(n), 3);
+
+        let n = 0b00000000000000000000000010000000;
+        assert_eq!(solution1(n), 1);
+
+        let n = 0b11111111111111111111111111111101;
+        assert_eq!(solution1(n), 31);
+    }
+
+    #[test]
+    fn test_solution2() {
+        let n = 0b00000000000000000000000000001011;
+        assert_eq!(solution2(n), 3);
+
+        let n = 0b00000000000000000000000010000000;
+        assert_eq!(solution2(n), 1);
+
+        let n = 0b11111111111111111111111111111101;
+        assert_eq!(solution2(n), 31);
+    }
+}