Add problem 2609: Find the Longest Balanced Substring of a Binary String

Author: EFanZh

src/lib.rs

@@ -1926,6 +1926,7 @@ pub mod problem_2598_smallest_missing_non_negative_integer_after_operations;
 pub mod problem_2600_k_items_with_the_maximum_sum;
 pub mod problem_2601_prime_subtraction_operation;
 pub mod problem_2602_minimum_operations_to_make_all_array_elements_equal;
+pub mod problem_2609_find_the_longest_balanced_substring_of_a_binary_string;
 
 #[cfg(test)]
 mod test_utilities;

src/problem_2609_find_the_longest_balanced_substring_of_a_binary_string/iterative.rs

@@ -0,0 +1,54 @@
+pub struct Solution;
+
+// ------------------------------------------------------ snip ------------------------------------------------------ //
+
+impl Solution {
+    pub fn find_the_longest_balanced_substring(s: String) -> i32 {
+        let mut zero_length = 0_u8;
+        let mut iter = s.bytes();
+        let mut result = 0;
+
+        'outer: while let Some(c) = iter.next() {
+            if c == b'0' {
+                zero_length += 1;
+            } else {
+                let mut one_length = 1;
+
+                loop {
+                    if let Some(c) = iter.next() {
+                        if c == b'0' {
+                            result = result.max(zero_length.min(one_length));
+                            zero_length = 1;
+
+                            break;
+                        }
+
+                        one_length += 1;
+                    } else {
+                        result = result.max(zero_length.min(one_length));
+
+                        break 'outer;
+                    }
+                }
+            }
+        }
+
+        i32::from(result * 2)
+    }
+}
+
+// ------------------------------------------------------ snip ------------------------------------------------------ //
+
+impl super::Solution for Solution {
+    fn find_the_longest_balanced_substring(s: String) -> i32 {
+        Self::find_the_longest_balanced_substring(s)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    #[test]
+    fn test_solution() {
+        super::super::tests::run::<super::Solution>();
+    }
+}

src/problem_2609_find_the_longest_balanced_substring_of_a_binary_string/mod.rs

@@ -0,0 +1,18 @@
+pub mod iterative;
+
+pub trait Solution {
+    fn find_the_longest_balanced_substring(s: String) -> i32;
+}
+
+#[cfg(test)]
+mod tests {
+    use super::Solution;
+
+    pub fn run<S: Solution>() {
+        let test_cases = [("01000111", 6), ("00111", 4), ("111", 0)];
+
+        for (s, expected) in test_cases {
+            assert_eq!(S::find_the_longest_balanced_substring(s.to_string()), expected);
+        }
+    }
+}