Find all Labels from given folders

Author: manjunatha

Diff for: problemsolving/BuildLabels.java

@@ -0,0 +1,93 @@
+package problemsolving;
+
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+/**
+ * Find all Labels from given folders
+ * 
+ * @author Manjunath Asundi
+ */
+public class BuildLabels {
+
+    /**
+     * Folder
+     */
+    static class Folder {
+        int id;
+        String displayName;
+        int parentId;
+
+        Folder(int id, String displayName, int parentId) {
+            this.id = id;
+            this.displayName = displayName;
+            this.parentId = parentId;
+        }
+    }
+
+    /**
+     * Label
+     */
+    static class Label {
+        String displayName;
+
+        Label(String displayName) {
+            this.displayName = displayName;
+        }
+    }
+
+    public static List<Label> buildLabels(List<Folder> fList) {
+        Map<Integer, Folder> rootChildMap = new HashMap<>();
+        List<Label> labels = new ArrayList<>();
+        for (int i = 0; i < fList.size(); i++) {
+            for (int j = 0; j < fList.size(); j++) {
+                if (fList.get(i).parentId == fList.get(j).id)
+                    rootChildMap.put(fList.get(i).id, fList.get(j));
+            }
+        }
+        Map<Integer, String> resultMap = new HashMap<>();
+        for (int i = 0; i < fList.size(); i++) {
+            Folder folder = fList.get(i);
+            String displayName = "";
+            if (folder.parentId != -1) {
+                displayName = buildLabelsUtil(rootChildMap, folder, displayName, resultMap);
+                resultMap.put(folder.id, displayName);
+            } else {
+                displayName = folder.displayName;
+                resultMap.put(folder.id, folder.displayName);
+            }
+            labels.add(new Label(displayName));
+        }
+        return labels;
+    }
+
+    public static String buildLabelsUtil(Map<Integer, Folder> rootChildMap, Folder folder, String displayName,
+            Map<Integer, String> resultMap) {
+        if (folder.parentId == -1)
+            return folder.displayName;
+        if (resultMap.containsKey(folder.id))
+            return resultMap.get(folder.id);
+        String resultString = displayName + folder.displayName;
+        String temp = buildLabelsUtil(rootChildMap, rootChildMap.get(folder.id), displayName, resultMap);
+        if (temp != null)
+            resultString = temp + "/" + resultString;
+        if (!resultMap.containsKey(folder.id))
+            resultMap.put(folder.id, resultString);
+        return resultString;
+    }
+
+    public static void main(String[] args) {
+        List<Folder> folderList = new ArrayList<Folder>();
+        folderList.add(new Folder(1, "A", -1));
+        folderList.add(new Folder(2, "B", 1));
+        folderList.add(new Folder(3, "C", 1));
+        folderList.add(new Folder(4, "D", 2));
+        folderList.add(new Folder(5, "E", 3));
+        List<Label> buildLabels = buildLabels(folderList);
+        for (Label label : buildLabels) {
+            System.out.println(label.displayName);
+        }
+    }
+}