Phone directory geeks solution

Phone directory geeks solution

  September 08, 2018    

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Problem:
As we see in our phone contact book when we type name of person it shows suggestions for every character typed by us in that name

Idea is to use TRIE.
Loop for every substring starting from 0 to 1..n
Search suggestions for that substring

Code:

import java.util.*;
import java.lang.*;
import java.io.*;
class trie
{
  HashMap<Character,trie> child;;
  boolean isEnd;
  trie()
  {
    isEnd=false;
    child=new HashMap<>();
  }
  void add(String a,trie root)
  {
  trie cur=root;
  for (int i=0;i<a.length() ;++i ) {
    if(cur.child.containsKey(a.charAt(i)))
    cur=cur.child.get(a.charAt(i));
    else
    {cur.child.put(a.charAt(i),new trie());
      cur=cur.child.get(a.charAt(i));
    }
  }
  cur.isEnd=true;
  }
   void search(String a,trie root)
   {
     trie cur=root;
     for (int i=0; i<a.length();++i ) {
       char t=a.charAt(i);
       trie node=cur.child.get(t);
       if(node==null)
       {System.out.print("0");
     return;}

     cur=node;
     }
     print(cur,a);
   }
   void print(trie root,String prefix)
   {
       if(root.isEnd)
       {System.out.print(prefix+" ");
       }
     for(char i='a';i<='z';++i)
     {
       trie node=root.child.get(i);
       
       if(node!=null)
       print(node,prefix+i);
     }
   }
}
class phoneDict
 {
  static trie root;
  public static void fn(String a[],int n,String q)
  {
    for (String t :a ) {
      root.add(t,root);
    }
    for(int i=1;i<=q.length();++i)
    {root.search(q.substring(0,i),root);
      System.out.println();
    }
  }
public static void main (String[] args)
{
Scanner ab=new Scanner(System.in);
int t=ab.nextInt();
while(t-->0)
{
    root=new trie();
    int n=ab.nextInt();
    String arr[]=new String[n];
    for(int i=0;i<n;++i)
    arr[i]=ab.next();
      fn(arr,n,ab.next());
    //System.out.println();
}
}
}