Create Web Crawler.java

varunu28 · web-flow · commit 7a448d00ac96 · 2019-10-20T20:32:25.000-07:00
diff --git a/Medium/Web Crawler.java b/Medium/Web Crawler.java
@@ -0,0 +1,31 @@
+/**
+ * // This is the HtmlParser's API interface.
+ * // You should not implement it, or speculate about its implementation
+ * interface HtmlParser {
+ *     public List<String> getUrls(String url) {}
+ * }
+ */
+class Solution {
+    public List<String> crawl(String startUrl, HtmlParser htmlParser) {
+        Set<String> visited = new HashSet<>();
+        Stack<String> stack = new Stack<>();
+        stack.push(startUrl);
+        String hostname = getHostname(startUrl);
+        while(!stack.isEmpty()) {
+            String popped = stack.pop();
+            visited.add(popped);
+            List<String> connectedUrls = htmlParser.getUrls(popped);
+            for (String url : connectedUrls) {
+                if (!visited.contains(url) && url.contains(hostname)) {
+                    stack.push(url);
+                }
+            }
+        }
+        return new ArrayList<>(visited);
+    }
+    
+    private String getHostname(String url) {
+        String[] splits = url.split("/");
+        return splits[2];
+    }
+}
