32:最长有效括号

src/main/java/leetcode/editor/cn/LongestValidParentheses.java

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+//给你一个只包含 '(' 和 ')' 的字符串，找出最长有效（格式正确且连续）括号子串的长度。 
+//
+// 
+//
+// 
+// 
+// 示例 1： 
+//
+// 
+//输入：s = "(()"
+//输出：2
+//解释：最长有效括号子串是 "()"
+// 
+//
+// 示例 2： 
+//
+// 
+//输入：s = ")()())"
+//输出：4
+//解释：最长有效括号子串是 "()()"
+// 
+//
+// 示例 3： 
+//
+// 
+//输入：s = ""
+//输出：0
+// 
+//
+// 
+//
+// 提示： 
+//
+// 
+// 0 <= s.length <= 3 * 10⁴ 
+// s[i] 为 '(' 或 ')' 
+// 
+// 
+// 
+// Related Topics 栈 字符串 动态规划 👍 1706 👎 0
+
+package leetcode.editor.cn;
+
+import javafx.util.Pair;
+
+import java.util.*;
+
+//32:最长有效括号
+public class LongestValidParentheses {
+    public static void main(String[] args) {
+        Solution solution = new LongestValidParentheses().new Solution();
+        solution.longestValidParentheses("(()");
+    }
+
+    //leetcode submit region begin(Prohibit modification and deletion)
+    class Solution {
+        public int longestValidParentheses(String s) {
+            Stack<Pair<String, Integer>> stack = new Stack<>();
+            while (s.startsWith(")")) {
+                s = s.substring(1);
+            }
+            while (s.endsWith("(")) {
+                s = s.substring(0, s.length() - 1);
+            }
+            List<Integer> list = new ArrayList<>();
+            for (int i = 0; i < s.length(); i++) {
+                if (s.charAt(i) == '(') {
+                    stack.add(new Pair<>("(", i));
+                } else if (!stack.isEmpty() && "(".equals(stack.peek().getKey())) {
+                    list.add(stack.pop().getValue());
+                    list.add(i);
+                } else {
+                    stack.add(new Pair<>(")", i));
+                }
+            }
+            if (list.size() == 0) {
+                return 0;
+            }
+            Collections.sort(list);
+            int max = 0;
+            int count = 1;
+            for (int i = 1; i < list.size(); i++) {
+                if (list.get(i) == list.get(i - 1) + 1) {
+                    count++;
+                } else {
+                    max = Math.max(max, count);
+                    count = 1;
+                }
+            }
+            return Math.max(max, count);
+        }
+    }
+//leetcode submit region end(Prohibit modification and deletion)
+
+}

src/main/java/leetcode/editor/cn/doc/content/LongestValidParentheses.md

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+<p>给你一个只包含 <code>'('</code> 和 <code>')'</code> 的字符串，找出最长有效（格式正确且连续）括号子串的长度。</p>
+
+<p> </p>
+
+<div class="original__bRMd">
+<div>
+<p><strong>示例 1：</strong></p>
+
+<pre>
+<strong>输入：</strong>s = "(()"
+<strong>输出：</strong>2
+<strong>解释：</strong>最长有效括号子串是 "()"
+</pre>
+
+<p><strong>示例 2：</strong></p>
+
+<pre>
+<strong>输入：</strong>s = ")()())"
+<strong>输出：</strong>4
+<strong>解释：</strong>最长有效括号子串是 "()()"
+</pre>
+
+<p><strong>示例 3：</strong></p>
+
+<pre>
+<strong>输入：</strong>s = ""
+<strong>输出：</strong>0
+</pre>
+
+<p> </p>
+
+<p><strong>提示：</strong></p>
+
+<ul>
+	<li><code>0 <= s.length <= 3 * 10<sup>4</sup></code></li>
+	<li><code>s[i]</code> 为 <code>'('</code> 或 <code>')'</code></li>
+</ul>
+</div>
+</div>
+<div><div>Related Topics</div><div><li>栈</li><li>字符串</li><li>动态规划</li></div></div><br><div><li>👍 1706</li><li>👎 0</li></div>