Sync LeetCode submission Runtime - 0 ms (100.00%), Memory - 17.8 MB (35.63%)

Author: jimit105

0020-valid-parentheses/README.md

@@ -11,24 +11,35 @@
 <p>&nbsp;</p>
 <p><strong class="example">Example 1:</strong></p>
 
-<pre>
-<strong>Input:</strong> s = &quot;()&quot;
-<strong>Output:</strong> true
-</pre>
+<div class="example-block">
+<p><strong>Input:</strong> <span class="example-io">s = &quot;()&quot;</span></p>
+
+<p><strong>Output:</strong> <span class="example-io">true</span></p>
+</div>
 
 <p><strong class="example">Example 2:</strong></p>
 
-<pre>
-<strong>Input:</strong> s = &quot;()[]{}&quot;
-<strong>Output:</strong> true
-</pre>
+<div class="example-block">
+<p><strong>Input:</strong> <span class="example-io">s = &quot;()[]{}&quot;</span></p>
+
+<p><strong>Output:</strong> <span class="example-io">true</span></p>
+</div>
 
 <p><strong class="example">Example 3:</strong></p>
 
-<pre>
-<strong>Input:</strong> s = &quot;(]&quot;
-<strong>Output:</strong> false
-</pre>
+<div class="example-block">
+<p><strong>Input:</strong> <span class="example-io">s = &quot;(]&quot;</span></p>
+
+<p><strong>Output:</strong> <span class="example-io">false</span></p>
+</div>
+
+<p><strong class="example">Example 4:</strong></p>
+
+<div class="example-block">
+<p><strong>Input:</strong> <span class="example-io">s = &quot;([])&quot;</span></p>
+
+<p><strong>Output:</strong> <span class="example-io">true</span></p>
+</div>
 
 <p>&nbsp;</p>
 <p><strong>Constraints:</strong></p>

0020-valid-parentheses/solution.py

@@ -1,29 +1,22 @@
-# Approach 1 - Stack
+# Approach 1: Stacks
 
 # Time: O(n)
 # Space: O(n)
 
 class Solution:
     def isValid(self, s: str) -> bool:
         stack = []
-        
-        mappings = {')': '(',
-                    ']':'[',
-                    '}':'{'}
-        
-        for char in s:            
-            # check if is it closing bracket
-            if char in mappings:
-                
-                # popping the last opening bracket, closing bracket is never pushed to the stack
-                last_element = stack.pop() if stack else '#'
-                
-                if mappings[char] != last_element:
-                    return False                
-                
-            # its char in opening bracket, append to stack
+
+        mapping = {')': "(", '}': '{', ']': '['}
+
+        for char in s:
+            if char in mapping:
+                top_element = stack.pop() if stack else '#'
+
+                if mapping[char] != top_element:
+                    return False
             else:
-                stack.append(char)              
-                
-        # if still there are elements in the stack, then return False
+                stack.append(char)
+
         return not stack
+