From 52aae558c9b71443b84913a8bcda0334e3e6f9ec Mon Sep 17 00:00:00 2001
From: Pandurang Lad <premlad961@gmail.com>
Date: Sun, 5 Nov 2023 13:35:21 +0530
Subject: [PATCH 1/2] feat: added solutions to lc problem: No.0020

Created file solution.cs for C# solution to lc problem: No.0020
---
 .../0020.Valid Parentheses/solutions.cs          | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)
 create mode 100644 solution/0000-0099/0020.Valid Parentheses/solutions.cs

diff --git a/solution/0000-0099/0020.Valid Parentheses/solutions.cs b/solution/0000-0099/0020.Valid Parentheses/solutions.cs
new file mode 100644
index 0000000000000..b35e035c0a336
--- /dev/null
+++ b/solution/0000-0099/0020.Valid Parentheses/solutions.cs	
@@ -0,0 +1,16 @@
+public class Solution {
+    public bool IsValid(string s) {
+        Stack<char> ch = new Stack<char>();
+            foreach (var item in s.ToCharArray())
+                if (item == '(')
+                    ch.Push(')');
+                else if (item == '[')
+                    ch.Push(']');
+                else if (item == '{')
+                    ch.Push('}');
+                else if (ch.Count == 0 || ch.Pop() != item)
+                    return false;
+
+            return ch.Count == 0;
+    }
+}

From bac99c1d5ce4108327a6127b26e7b03af964d10a Mon Sep 17 00:00:00 2001
From: Libin YANG <contact@yanglibin.info>
Date: Sun, 5 Nov 2023 23:01:39 +0800
Subject: [PATCH 2/2] Update solutions.cs

---
 .../0020.Valid Parentheses/solutions.cs       | 25 ++++++++++---------
 1 file changed, 13 insertions(+), 12 deletions(-)

diff --git a/solution/0000-0099/0020.Valid Parentheses/solutions.cs b/solution/0000-0099/0020.Valid Parentheses/solutions.cs
index b35e035c0a336..f0b79f30fbc19 100644
--- a/solution/0000-0099/0020.Valid Parentheses/solutions.cs	
+++ b/solution/0000-0099/0020.Valid Parentheses/solutions.cs	
@@ -1,16 +1,17 @@
 public class Solution {
     public bool IsValid(string s) {
-        Stack<char> ch = new Stack<char>();
-            foreach (var item in s.ToCharArray())
-                if (item == '(')
-                    ch.Push(')');
-                else if (item == '[')
-                    ch.Push(']');
-                else if (item == '{')
-                    ch.Push('}');
-                else if (ch.Count == 0 || ch.Pop() != item)
-                    return false;
-
-            return ch.Count == 0;
+        Stack<char> stk = new Stack<char>();
+        foreach (var c in s.ToCharArray()) {
+            if (c == '(') {
+                stk.Push(')');
+            } else if (c == '[') {
+                stk.Push(']');
+            } else if (c == '{') {
+                stk.Push('}');
+            } else if (stk.Count == 0 || stk.Pop() != c) {
+                return false;
+            }
+        }
+        return stk.Count == 0;
     }
 }