32. Longest Valid Parentheses

32. Longest Valid Parentheses/32. Longest Valid Parentheses.csproj

@@ -0,0 +1,11 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>net10.0</TargetFramework>
+    <RootNamespace>_32._Longest_Valid_Parentheses</RootNamespace>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+  </PropertyGroup>
+
+</Project>

32. Longest Valid Parentheses/Program.cs

@@ -0,0 +1,5 @@
+var sol = new Solution();
+
+// System.Console.WriteLine(sol.LongestValidParentheses(")()())"));
+// System.Console.WriteLine(sol.LongestValidParentheses("()(()"));
+System.Console.WriteLine(sol.LongestValidParentheses("()(())"));

32. Longest Valid Parentheses/Solution.cs

@@ -0,0 +1,43 @@
+public class Solution
+{
+    struct Item
+    {
+        public char Sym;
+        public int Count;
+        public char? PrevSym;
+    }
+
+    public int LongestValidParentheses(string s)
+    {
+        var stack = new Stack<Item>();
+        var answer = 0;
+        foreach (var ch in s)
+        {
+            if (stack.Count > 0 && (stack.Peek().Sym == '(' || stack.Peek().PrevSym == '(') && ch == ')')
+            {
+                var prev = stack.Pop();
+                var count = 2;
+                if (prev.Sym == '#')
+                {
+                    stack.Pop();
+                    count += prev.Count;
+                }
+                while (stack.Count > 0 && stack.Peek().Sym == '#')
+                    count += stack.Pop().Count;
+                char? prevSym = null;
+                if (stack.Count > 0)
+                    prevSym = stack.Peek().Sym;
+                stack.Push(new Item() { Sym = '#', Count = count, PrevSym = prevSym });
+                answer = Math.Max(answer, count);
+            }
+            else
+            {
+                stack.Push(new Item() { Sym = ch, Count = 0 });
+
+
+            }
+        }
+
+        return answer;
+    }
+}

Leetcode.sln

@@ -191,6 +191,8 @@ Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "26. Remove Duplicates from
 EndProject
 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "31. Next Permutation", "31. Next Permutation\31. Next Permutation.csproj", "{DC76DEDE-AF9D-429B-B53B-204E89E90EA0}"
 EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "32. Longest Valid Parentheses", "32. Longest Valid Parentheses\32. Longest Valid Parentheses.csproj", "{9BD247FC-E91E-4FBD-9E97-6B917E4606D2}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -1329,6 +1331,18 @@ Global
 		{DC76DEDE-AF9D-429B-B53B-204E89E90EA0}.Release|x64.Build.0 = Release|Any CPU
 		{DC76DEDE-AF9D-429B-B53B-204E89E90EA0}.Release|x86.ActiveCfg = Release|Any CPU
 		{DC76DEDE-AF9D-429B-B53B-204E89E90EA0}.Release|x86.Build.0 = Release|Any CPU
+		{9BD247FC-E91E-4FBD-9E97-6B917E4606D2}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{9BD247FC-E91E-4FBD-9E97-6B917E4606D2}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{9BD247FC-E91E-4FBD-9E97-6B917E4606D2}.Debug|x64.ActiveCfg = Debug|Any CPU
+		{9BD247FC-E91E-4FBD-9E97-6B917E4606D2}.Debug|x64.Build.0 = Debug|Any CPU
+		{9BD247FC-E91E-4FBD-9E97-6B917E4606D2}.Debug|x86.ActiveCfg = Debug|Any CPU
+		{9BD247FC-E91E-4FBD-9E97-6B917E4606D2}.Debug|x86.Build.0 = Debug|Any CPU
+		{9BD247FC-E91E-4FBD-9E97-6B917E4606D2}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{9BD247FC-E91E-4FBD-9E97-6B917E4606D2}.Release|Any CPU.Build.0 = Release|Any CPU
+		{9BD247FC-E91E-4FBD-9E97-6B917E4606D2}.Release|x64.ActiveCfg = Release|Any CPU
+		{9BD247FC-E91E-4FBD-9E97-6B917E4606D2}.Release|x64.Build.0 = Release|Any CPU
+		{9BD247FC-E91E-4FBD-9E97-6B917E4606D2}.Release|x86.ActiveCfg = Release|Any CPU
+		{9BD247FC-E91E-4FBD-9E97-6B917E4606D2}.Release|x86.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE