diff --git a/leetcode/20/node_Wanghonglu.md b/leetcode/20/node_Wanghonglu.md
new file mode 100644
index 0000000..45d5a4d
--- /dev/null
+++ b/leetcode/20/node_Wanghonglu.md
@@ -0,0 +1,112 @@
+class Solution {
+public:
+    bool isValid(string s) {
+        char  elem=0,left_elem=0,right_elem=0;
+        Stack *ptr = new Stack( (int)s.length() );
+        for( int i=0;i<s.size();i++ )
+        {
+            elem = s[i];
+            switch( elem )
+            {
+            case '[':
+            case '(':
+            case '{':
+            ptr->PushStack(elem);
+            break;
+            case ']':
+            case ')':
+            case '}':
+            {
+                ptr->GetTopStack(left_elem);
+                switch( left_elem )
+                {
+                    case '[':
+                    right_elem = ']';
+                    break;
+                    case '(':
+                    right_elem = ')';
+                    break;
+                    case '{':
+                    right_elem = '}';
+                    break;
+                }
+                if( right_elem == elem )
+                {
+                    ptr->PopStack();
+                    break;
+                }
+                else
+                {        
+                    delete ptr;
+                    return false;
+                }
+            }
+            default:
+            {
+                delete ptr;
+                return false;
+            }
+
+            }
+        }
+        if(ptr->IsEmptyStack())
+        {
+            delete ptr;
+            return true;
+        }
+        delete ptr;
+        return false;
+    }
+class Stack{
+public:
+    Stack( int size )
+    {
+        m_size = size;
+        m_ptr = new char[size];
+        memset( m_ptr, 0x00, size );
+        m_top = 0;
+    }
+    ~Stack()
+    {
+        delete []m_ptr;
+        m_top = 0;
+        m_size = 0;
+    }
+    bool IsFullStack()
+    {
+        return m_size == m_top;
+    }
+    bool IsEmptyStack()
+    {
+        return m_top ==0;
+    }
+    bool PushStack( char elem )
+    {
+        if( IsFullStack() )
+            return false;
+        m_ptr[m_top] = elem;
+        m_top++;
+        return true;
+    }
+    bool PopStack( )
+    {
+        if( IsEmptyStack())
+            return false;
+        m_top--;
+        return true;
+    }
+    bool GetTopStack( char& elem )
+    {
+        if( IsEmptyStack() )
+            return false;
+        elem = m_ptr[m_top-1];
+        return true;
+    }
+private:
+    char* m_ptr;
+    int   m_top;
+    int   m_size;
+};
+
+    
+};