solve 22

Author: Zhang Xiaodong

src/solution/mod.rs

@@ -17,3 +17,4 @@ mod s0018_4sum;
 mod s0019_remove_nth_node_from_end_of_list;
 mod s0020_valid_parentheses;
 mod s0021_merge_two_sorted_lists;
+mod s0022_generate_parentheses;

src/solution/s0022_generate_parentheses.rs

@@ -0,0 +1,68 @@
+/**
+ * [22] 括号生成
+ *
+ * 数字 n 代表生成括号的对数，请你设计一个函数，用于能够生成所有可能的并且 有效的 括号组合。
+ *  
+ * 示例 1：
+ *
+ * 输入：n = 3
+ * 输出：["((()))","(()())","(())()","()(())","()()()"]
+ *
+ * 示例 2：
+ *
+ * 输入：n = 1
+ * 输出：["()"]
+ *
+ *  
+ * 提示：
+ *
+ * 	1 <= n <= 8
+ *
+ */
+pub struct Solution {}
+
+// problem: https://leetcode.cn/problems/generate-parentheses/
+// discuss: https://leetcode.cn/problems/generate-parentheses/discuss/?currentPage=1&orderBy=most_votes&query=
+
+// submission codes start here
+
+impl Solution {
+    pub fn generate_parenthesis(n: i32) -> Vec<String> {
+        Self::gen(0, 0, n)
+    }
+
+    fn gen(l: i32, r: i32, n: i32) -> Vec<String> {
+        if l > n || l < r {
+            return vec![];
+        }
+        if l == n && l == r {
+            return vec!["".to_string()];
+        }
+        let mut res = vec![];
+        let subs = Self::gen(l + 1, r, n);
+        for s in subs {
+            res.push(format!("({}", s));
+        }
+        let subs = Self::gen(l, r + 1, n);
+        for s in subs {
+            res.push(format!("){}", s));
+        }
+        res
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_22() {
+        assert_eq!(Solution::generate_parenthesis(1), vec!["()".to_string()]);
+        assert_eq!(
+            Solution::generate_parenthesis(3),
+            vec!["((()))", "(()())", "(())()", "()(())", "()()()"]
+        );
+    }
+}