From e9be4598c402381879ef6cc310a11f8dfd651a74 Mon Sep 17 00:00:00 2001
From: juan <juancloudcomputing@protonmail.com>
Date: Sun, 3 Jul 2022 09:58:52 +0800
Subject: [PATCH] vault backup: 2022-07-03 09:58:52

---
 CS notes/pages/Leetcode  Valid-Parentheses.md | 40 ++++++++++++++++++-
 .../Leetcode Implement-Queue-Using-Stacks.md  | 35 ++++++++++++++++
 2 files changed, 73 insertions(+), 2 deletions(-)
 create mode 100644 CS notes/pages/Leetcode Implement-Queue-Using-Stacks.md

diff --git a/CS notes/pages/Leetcode  Valid-Parentheses.md b/CS notes/pages/Leetcode  Valid-Parentheses.md
index a9ee0e9..10dc50e 100644
--- a/CS notes/pages/Leetcode  Valid-Parentheses.md	
+++ b/CS notes/pages/Leetcode  Valid-Parentheses.md	
@@ -9,7 +9,7 @@
 > ##### Additional tags:
 > #leetcode
 > ##### Revisions:
-> Initial encounter: 2022-06-16
+> 1st revision: 2022-07-03 optimize code
 
 ##### Related topics:
 ```expander
@@ -60,6 +60,41 @@ Basic stack usage.
 Can be implemented using std_stack or stc_vector.
 obviously i should use std_stack.
 ### Solution
+1st revision: optimized code
+```cpp
+class Solution {
+public:
+  bool isValid(string s) {
+    stack<char> st;
+
+    char pairs[3][2] = {'(', ')', '{', '}', '[', ']'};
+    const int pairSize = 3;
+
+    for (char c : s) {
+      for (int i = 0; i < pairSize; i++) {
+        if (pairs[i][0] == c) {
+          // {([
+          st.push(c);
+        } else if (pairs[i][1] == c) {
+          // ]})
+          if (st.empty()) {
+            // empty
+            return false;
+          } else if (st.top() != pairs[i][0]) {
+            // mismatch
+            return false;
+          } else {
+            st.pop();
+          }
+        }
+      }
+    }
+
+    return st.empty();
+  }
+};
+
+```
 
 ```cpp
 class Solution {
@@ -99,4 +134,5 @@ public:
   }
 };
 
-```
\ No newline at end of file
+```
+
diff --git a/CS notes/pages/Leetcode Implement-Queue-Using-Stacks.md b/CS notes/pages/Leetcode Implement-Queue-Using-Stacks.md
new file mode 100644
index 0000000..b1eaedf
--- /dev/null
+++ b/CS notes/pages/Leetcode Implement-Queue-Using-Stacks.md	
@@ -0,0 +1,35 @@
+# Leetcode Implement-Queue-Using-Stacks
+
+#### 2022-07-03 09:52
+
+> ##### Data structures:
+> #DS #stack #queue
+> ##### Difficulty:
+> #coding_problem #difficulty-easy 
+> ##### Additional tags:
+> #leetcode  #CS_list_need_understanding 
+> ##### Revisions:
+> N/A
+
+##### Related topics:
+```expander
+tag:#stack tag:#queue 
+```
+ 
+ 
+
+##### Links:
+- [Link to problem]()
+___
+### Problem
+
+#### Examples
+
+#### Constraints
+
+### Thoughts
+
+> [!summary]
+> This is a #template_remove_me
+
+### Solution