Merge pull request #10 from rust-interview/dev

add bitwise_and_of_numbers_range

Author: 0xmountaintop

.travis.yml

@@ -4,7 +4,6 @@ sudo: required
 
 os:
   - linux
-  - windows
   - osx
 
 rust:

README.md

@@ -52,10 +52,10 @@ cargo test
 0137 | [Single Number II](https://leetcode.com/problems/single-number-ii/) | [C++](https://github.com/kamyu104/LeetCode-Solutions/blob/master/C++/single-number-ii.cpp), [Python](https://github.com/kamyu104/LeetCode-Solutions/blob/master/Python/single-number-ii.py) <br> [Rust](./kamyu104/src/single_number_ii.rs) | _O(n)_ | _O(1)_          | Medium         |||
 0190 | [Reverse Bits](https://leetcode.com/problems/reverse-bits/)  | [C++](https://github.com/kamyu104/LeetCode-Solutions/blob/master/C++/reverse-bits.cpp), [Python](https://github.com/kamyu104/LeetCode-Solutions/blob/master/Python/reverse-bits.py) <br> [Rust](./kamyu104/src/reverse_bits.rs) | _O(1)_        | _O(1)_          | Easy           |||
 0191  |[Number of 1 Bits](https://leetcode.com/problems/number-of-1-bits/) | [C++](https://github.com/kamyu104/LeetCode-Solutions/blob/master/C++/number-of-1-bits.cpp), [Python](https://github.com/kamyu104/LeetCode-Solutions/blob/master/Python/number-of-1-bits.py) <br> [Rust](./kamyu104/src/number_of_1_bits.rs) | _O(1)_ | _O(1)_          | Easy           |||
+0201 | [Bitwise AND of Numbers Range](https://leetcode.com/problems/bitwise-and-of-numbers-range/) | [C++](https://github.com/kamyu104/LeetCode-Solutions/blob/master/C++/bitwise-and-of-numbers-range.cpp), [Python](https://github.com/kamyu104/LeetCode-Solutions/blob/master/Python/bitwise-and-of-numbers-range.py) <br> [Rust](./kamyu104/src/bitwise_and_of_numbers_range.rs) | _O(1)_ | _O(1)_ | Medium ||
 
@@ -0,0 +1,40 @@
@@ -0,0 +1,40 @@
+// Time:  O(1)
+// Space: O(1)
+
+pub struct Solution1 {}
+pub struct Solution2 {}
+
+impl Solution1 {
+    pub fn range_bitwise_and(m: u32, mut n: u32) -> u32 {
+        while m < n {
+            // Remove the last bit 1 until n <= m.
+            n &= n - 1;
+        }
+        n
+    }
+}
+
+impl Solution2 {
+    pub fn range_bitwise_and(m: u32, n: u32) -> u32 {
+        let (mut i, mut diff): (u32, u32) = (0, n - m);
+        while diff != 0 {
+            diff >>= 1;
+            i += 1;
+        }
+        n & m >> i << i
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_range_bitwise_and() {
+        assert_eq!(Solution1::range_bitwise_and(5, 7), 4);
+        assert_eq!(Solution1::range_bitwise_and(0, 1), 0);
+
+        assert_eq!(Solution2::range_bitwise_and(5, 7), 4);
+        assert_eq!(Solution2::range_bitwise_and(0, 1), 0);
+    }
+}
@@ -1,3 +1,4 @@
+mod bitwise_and_of_numbers_range;
 mod number_of_1_bits;
 mod reverse_bits;
 mod single_number;

kamyu104/src/main.rs

@@ -0,0 +1,40 @@
+// Time:  O(1)
+// Space: O(1)
+
+pub struct Solution1 {}
+pub struct Solution2 {}
+
+impl Solution1 {
+    pub fn range_bitwise_and(m: u32, mut n: u32) -> u32 {
+        while m < n {
+            // Remove the last bit 1 until n <= m.
+            n &= n - 1;
+        }
+        n
+    }
+}
+
+impl Solution2 {
+    pub fn range_bitwise_and(m: u32, n: u32) -> u32 {
+        let (mut i, mut diff): (u32, u32) = (0, n - m);
+        while diff != 0 {
+            diff >>= 1;
+            i += 1;
+        }
+        n & m >> i << i
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_range_bitwise_and() {
+        assert_eq!(Solution1::range_bitwise_and(5, 7), 4);
+        assert_eq!(Solution1::range_bitwise_and(0, 1), 0);
+
+        assert_eq!(Solution2::range_bitwise_and(5, 7), 4);
+        assert_eq!(Solution2::range_bitwise_and(0, 1), 0);
+    }
+}

@@ -1,3 +1,4 @@
+mod bitwise_and_of_numbers_range;
 mod number_of_1_bits;
 mod reverse_bits;
 mod single_number;