From 977b24d3364a09a594d0bbb243f26e5aaf541487 Mon Sep 17 00:00:00 2001
From: guimalonso <guilherme.malonso@gmail.com>
Date: Sun, 17 Oct 2021 23:00:05 -0300
Subject: [PATCH] feat: add valid-parenthesis solution in php

---
 .../valid-parenthesis.php                     | 39 +++++++++++++++++++
 1 file changed, 39 insertions(+)
 create mode 100644 leetcode/20 - validparenthesis/valid-parenthesis.php

diff --git a/leetcode/20 - validparenthesis/valid-parenthesis.php b/leetcode/20 - validparenthesis/valid-parenthesis.php
new file mode 100644
index 0000000..e3feff9
--- /dev/null
+++ b/leetcode/20 - validparenthesis/valid-parenthesis.php	
@@ -0,0 +1,39 @@
+<?php
+
+class ValidParenthesisSolution {
+
+    /**
+     * @param String $s
+     * @return Boolean
+     */
+    function isValid($s) {
+        $stack = [];
+        $symbols = [
+            ')' => '(',
+            ']' => '[',
+            '}' => '{'
+        ];
+        
+        for ($index = 0; $index < strlen($s); $index++) {
+            $character = $s[$index];
+            switch ($character) {
+                case '(':
+                case '[':
+                case '{':
+                    $stack[] = $character;
+                    break;
+                case ')':
+                case ']':
+                case '}':
+                    if (count($stack) === 0 || $stack[count($stack)-1] !== $symbols[$character]) {
+                        return false;
+                    }
+                    
+                    array_pop($stack);
+                    break;
+            }
+        }
+        
+        return count($stack) === 0;
+    }
+}
\ No newline at end of file