20240707 Finished

src/problem/mod.rs

@@ -168,4 +168,5 @@ mod p212_word_search_ii;
 mod p17_letter_combinations_of_a_phone_number;
 mod p77_combinations;
 mod p46_permutations;
-mod p39_combination_sum;
+mod p39_combination_sum;
+mod p22_generate_parentheses;

src/problem/p22_generate_parentheses.rs

@@ -0,0 +1,50 @@
+/**
+ * [22] Generate Parentheses
+ */
+pub struct Solution {}
+
+
+// submission codes start here
+
+impl Solution {
+    pub fn generate_parenthesis(n: i32) -> Vec<String> {
+        let n = n as usize;
+        let mut result = vec![];
+        let mut path = Vec::with_capacity(n * 2);
+        
+        Self::backtrace(n, 0, &mut path, &mut result);
+        
+        result
+    }
+    
+    fn backtrace(left: usize, right: usize, path: &mut Vec<char>, result: &mut Vec<String>) {
+        if left == 0 && right == 0 {
+            let t = path.clone();
+            result.push(t.iter().collect());
+            return;
+        }
+        
+        if left != 0 {
+            path.push('(');
+            Self::backtrace(left - 1, right + 1, path, result);
+            path.pop();
+        }
+        
+        if right != 0 {
+            path.push(')');
+            Self::backtrace(left, right - 1, path, result);
+            path.pop();
+        }
+    } 
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_22() {
+    }
+}