LC 2220. Minimum Bit Flips to Convert Number (Rust)

Author: raul-sauco

README.md

@@ -651,6 +651,7 @@ Solutions to LeetCode problems. The first column links to the problem in LeetCod
 | [2187. Minimum Time to Complete Trips][lc2187]                                                | 🟠 Medium  | [![python](res/py.png)][lc2187py] [![rust](res/rs.png)][lc2187rs]                                     |
 | [2215. Find the Difference of Two Arrays][lc2215]                                             | 🟢 Easy    | [![python](res/py.png)][lc2215py] [![rust](res/rs.png)][lc2215rs]                                     |
 | [2218. Maximum Value of K Coins From Piles][lc2218]                                           | 🔴 Hard    | [![python](res/py.png)][lc2218py] [![rust](res/rs.png)][lc2218rs]                                     |
+| [2220. Minimum Bit Flips to Convert Number][lc2220]                                           | 🟢 Easy    | [![rust](res/rs.png)][lc2220rs]                                                                       |
 | [2225. Find Players With Zero or One Losses][lc2225]                                          | 🟢 Easy    | [![python](res/py.png)][lc2225py]                                                                     |
 | [2244. Minimum Rounds to Complete All Tasks][lc2244]                                          | 🟠 Medium  | [![python](res/py.png)][lc2244py]                                                                     |
 | [2246. Longest Path With Different Adjacent Characters][lc2246]                               | 🔴 Hard    | [![python](res/py.png)][lc2246py]                                                                     |
@@ -2188,6 +2189,8 @@ Solutions to LeetCode problems. The first column links to the problem in LeetCod
 [lc2218]: https://leetcode.com/problems/maximum-value-of-k-coins-from-piles/
 [lc2218py]: leetcode/maximum-value-of-k-coins-from-piles.py
 [lc2218rs]: leetcode/maximum-value-of-k-coins-from-piles.rs
+[lc2220]: https://leetcode.com/problems/minimum-bit-flips-to-convert-number/
+[lc2220rs]: leetcode/minimum-bit-flips-to-convert-number.rs
 [lc2225]: https://leetcode.com/problems/find-players-with-zero-or-one-losses/
 [lc2225py]: leetcode/find-players-with-zero-or-one-losses.py
 [lc2244]: https://leetcode.com/problems/minimum-rounds-to-complete-all-tasks/

leetcode/minimum-bit-flips-to-convert-number.rs

@@ -0,0 +1,70 @@
+// 2220. Minimum Bit Flips to Convert Number
+// 🟢 Easy
+//
+// https://leetcode.com/problems/minimum-bit-flips-to-convert-number/
+//
+// Tags: Bit Manipulation
+
+struct Solution;
+impl Solution {
+    /// One solution is to XOR the input numbers and return the number of 1 bits in the result.
+    ///
+    /// Time complexity: O(log2(max(m,n))) - The built-in count_ones function's complexity.
+    /// Space complexity: O(1) - Constant extra memory used.
+    ///
+    /// Runtime 0 ms Beats 100%
+    /// Memory 2.08 MB Beats 84%
+    #[allow(dead_code)]
+    pub fn min_bit_flips_built_in(start: i32, goal: i32) -> i32 {
+        (start ^ goal).count_ones() as _
+    }
+
+    /// A neat method using Brian Kernighan’s Algorithm, it counts one values skipping values that
+    /// we are not interested on.
+    ///
+    /// Time complexity: O(log2(n)) - Where n is the result.
+    /// Space complexity: O(1) - Constant extra memory used.
+    ///
+    /// Runtime 0 ms Beats 100%
+    /// Memory 2.19 MB Beats 15%
+    #[allow(dead_code)]
+    pub fn min_bit_flips(start: i32, goal: i32) -> i32 {
+        let mut rem = start ^ goal;
+        let mut res = 0;
+        while rem > 0 {
+            rem &= rem - 1;
+            res += 1;
+        }
+        res
+    }
+}
+
+// Tests.
+fn main() {
+    let tests = [(10, 7, 3), (3, 4, 3)];
+    println!("\n\x1b[92m» Running {} tests...\x1b[0m", tests.len());
+    let mut success = 0;
+    for (i, t) in tests.iter().enumerate() {
+        let res = Solution::min_bit_flips(t.0, t.1);
+        if res == t.2 {
+            success += 1;
+            println!("\x1b[92m✔\x1b[95m Test {} passed!\x1b[0m", i);
+        } else {
+            println!(
+                "\x1b[31mx\x1b[95m Test {} failed expected: {:?} but got {}!!\x1b[0m",
+                i, t.1, res
+            );
+        }
+    }
+    println!();
+    if success == tests.len() {
+        println!("\x1b[30;42m✔ All tests passed!\x1b[0m")
+    } else if success == 0 {
+        println!("\x1b[31mx \x1b[41;37mAll tests failed!\x1b[0m")
+    } else {
+        println!(
+            "\x1b[31mx\x1b[95m {} tests failed!\x1b[0m",
+            tests.len() - success
+        )
+    }
+}