HTML Tag Matching with Stacks

Problem Solving using Stack and Queue

HTML Tag Matching

• In HTML, each opening tag should pair with a matching closing tag (e.g., <p> with </p>, <div> with </div>, etc.)
• A well-formed HTML document should have matching tags, although most browsers tolerate some mismatching tags
• The checking of whether an HTML file has matching tags can be done using a stack

Stack-based Solution

• Read the entire HTML document into a string
• Make a left-to-right pass through the string, tracking progress with an index j
• Use the indexOf method to locate the > characters that define the tags
• Use the substring method to extract the tag contents
• Push opening tags onto the stack and match them against closing tags as they are popped from the stack
• If an opening tag is found, push it onto the stack
• If a closing tag is found, check if the stack is empty or if the tag doesn't match the top of the stack; if so, return false

Method Implementation

• public static boolean isHTMLMatched(String html) is a method that checks if an HTML document has matching tags
• The method uses a stack to store the opening tags
• It returns false if an invalid tag is found or if there's a mismatched tag