rs: add «201. Bitwise AND of Numbers Range»

Signed-off-by: Matej Focko <mfocko@redhat.com>

rs/bitwise-and-of-numbers-range.rs

@@ -0,0 +1,21 @@
+impl Solution {
+    fn discarded(mut left: i32, mut right: i32) -> i32 {
+        let mut counter = 0;
+
+        while left != right {
+            left >>= 1;
+            right >>= 1;
+
+            counter += 1;
+        }
+
+        counter
+    }
+
+    pub fn range_bitwise_and(left: i32, right: i32) -> i32 {
+        let discarded_bits = Solution::discarded(left, right);
+        let mask = !((1 << discarded_bits) - 1);
+
+        left & mask
+    }
+}