From 156d8fdd92b07c6ba74ed68ee9e8cd092c106024 Mon Sep 17 00:00:00 2001
From: SevenMonths <qinwen_shuai@163.com>
Date: Fri, 27 May 2022 14:21:41 +0800
Subject: [PATCH] =?UTF-8?q?=E5=A2=9E=E5=8A=A0(0020.=E6=9C=89=E6=95=88?=
 =?UTF-8?q?=E7=9A=84=E6=8B=AC=E5=8F=B7.md)=EF=BC=9APHP=E7=89=88=E6=9C=AC?=
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---
 problems/0020.有效的括号.md | 28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)

diff --git a/problems/0020.有效的括号.md b/problems/0020.有效的括号.md
index 7bb7f746..5e468549 100644
--- a/problems/0020.有效的括号.md
+++ b/problems/0020.有效的括号.md
@@ -401,5 +401,33 @@ bool isValid(char * s){
 }
 ```
 
+PHP:
+```php
+// https://www.php.net/manual/zh/class.splstack.php
+class Solution
+{
+    function isValid($s){
+        $stack = new SplStack();
+        for ($i = 0; $i < strlen($s); $i++) {
+            if ($s[$i] == "(") {
+                $stack->push(')');
+            } else if ($s[$i] == "{") {
+                $stack->push('}');
+            } else if ($s[$i] == "[") {
+                $stack->push(']');
+            // 2、遍历匹配过程中，发现栈内没有要匹配的字符 return false
+            // 3、遍历匹配过程中，栈已为空，没有匹配的字符了，说明右括号没有找到对应的左括号 return false
+            } else if ($stack->isEmpty() || $stack->top() != $s[$i]) {
+                return false;
+            } else {//$stack->top() == $s[$i]
+                $stack->pop();
+            }
+        }
+        // 1、遍历完，但是栈不为空,说明有相应的括号没有被匹配,return false
+        return $stack->isEmpty();
+    }
+}
+```
+
 -----------------------
 <div align="center"><img src=https://code-thinking.cdn.bcebos.com/pics/01二维码一.jpg width=500> </img></div>