二刷20

Author: diguage

docs/0020-valid-parentheses.adoc

@@ -54,10 +54,32 @@ Note that an empty string is also considered valid.
 *Output:* true
 ----
 
+== 思路分析
 
 [[src-0020]]
+[tabs]
+====
+一刷::
++
+--
 [{java_src_attr}]
 ----
 include::{sourcedir}/_0020_ValidParentheses.java[tag=answer]
 ----
+--
+
+二刷::
++
+--
+[{java_src_attr}]
+----
+include::{sourcedir}/_0020_ValidParentheses_2.java[tag=answer]
+----
+--
+====
+
+== 参考资料
+
+. https://leetcode.cn/problems/valid-parentheses/solutions/373578/you-xiao-de-gua-hao-by-leetcode-solution/?envType=study-plan-v2&envId=selected-coding-interview[20. 有效的括号 - 官方题解^]
+
 

logbook/202406.adoc

@@ -474,6 +474,11 @@
 |{doc_base_url}/0206-reverse-linked-list.adoc[题解]
 |递给解法非常妙！
 
+|{counter:codes}
+|{leetcode_base_url}/valid-parentheses/[20. Valid Parentheses^]
+|{doc_base_url}/0020-valid-parentheses.adoc[题解]
+|栈
+
 |===
 
 截止目前，本轮练习一共完成 {codes} 道题。

src/main/java/com/diguage/algo/leetcode/_0020_ValidParentheses.java

@@ -62,6 +62,9 @@ public class _0020_ValidParentheses {
      * Runtime: 2 ms, faster than 60.99% of Java online submissions for Valid Parentheses.
      *
      * Memory Usage: 34.2 MB, less than 100.00% of Java online submissions for Valid Parentheses.
+     *
+     * @author D瓜哥 · https://www.diguage.com
+     * @since 2019-07-26 08:12
      */
     public boolean isValid(String s) {
         if (Objects.isNull(s) || s.length() == 0) {

src/main/java/com/diguage/algo/leetcode/_0020_ValidParentheses_2.java

@@ -0,0 +1,42 @@
+package com.diguage.algo.leetcode;
+
+import java.util.Deque;
+import java.util.LinkedList;
+
+public class _0020_ValidParentheses_2 {
+  // tag::answer[]
+
+  /**
+   * @author D瓜哥 · https://www.diguage.com
+   * @since 2024-09-13 16:51:17
+   */
+  public boolean isValid(String s) {
+    Deque<Character> stack = new LinkedList<>();
+    for (int i = 0; i < s.length(); i++) {
+      char c = s.charAt(i);
+      if (c == '(' || c == '[' || c == '{') {
+        stack.addLast(c);
+      } else if (c == ')') {
+        if (stack.isEmpty() || stack.peekLast() != '(') {
+          return false;
+        } else {
+          stack.removeLast();
+        }
+      } else if (c == ']') {
+        if (stack.isEmpty() || stack.peekLast() != '[') {
+          return false;
+        } else {
+          stack.removeLast();
+        }
+      } else if (c == '}') {
+        if (stack.isEmpty() || stack.peekLast() != '{') {
+          return false;
+        } else {
+          stack.removeLast();
+        }
+      }
+    }
+    return stack.isEmpty();
+  }
+  // end::answer[]
+}