Given a sequence of words, print all anagrams together using STL

Given an array of words, print all anagrams together. 

For example, 

Input: array = {“cat”, “dog”, “tac”, “god”, “act”}
output: cat tac act, dog god
Explanation: cat tac and act are anagrams 
and dog and god are anagrams as 
they have the same set of characters.

Input: array = {“abc”, “def”, “ghi”}
output: abc, def, ghi
Explanation: There are no anagrams in the array.

Other approaches are discussed herein these posts:  

• given-a-sequence-of-words-print-all-anagrams-together
• given-a-sequence-of-words-print-all-anagrams-together-set-2

Approach: This is a HashMap solution using C++ Standard Template Library which stores the Key-Value Pair. In the hashmap, the key will be the sorted set of characters and value will be the output string. Two anagrams will be similar when their characters are sorted. Now,  

1. Store the vector elements in HashMap with key as the sorted string.
2. If the key is same, then add the string to the value of HashMap(string vector).
3. Traverse the HashMap and print the anagram strings.

Implementation:

C++

// C++ program for finding all anagram
// pairs in the given array
#include <algorithm>
#include <iostream>
#include <unordered_map>
#include <vector>
using namespace std;

// Utility function for
// printing anagram list
void printAnagram(unordered_map<string,vector<string> >& store)
{
    for (auto it:store)
    {
        vector<string> temp_vec(it.second);
        int size = temp_vec.size();

        for (int i = 0; i < size; i++)
        cout << temp_vec[i] << " ";

        cout << "\n";
    }
}

// Utility function for storing
// the vector of strings into HashMap
void storeInMap(vector<string>& vec)
{
    unordered_map<string,vector<string> > store;

    for (int i = 0; i < vec.size(); i++)
    {
        string tempString(vec[i]);

          // sort the string
        sort(tempString.begin(),tempString.end());

          // make hash of a sorted string
        store[tempString].push_back(vec[i]);
    }

    // print utility function for printing
    // all the anagrams
    printAnagram(store);
}

// Driver code
int main()
{
    // initialize vector of strings
    vector<string> arr;
    arr.push_back("geeksquiz");
    arr.push_back("geeksforgeeks");
    arr.push_back("abcd");
    arr.push_back("forgeeksgeeks");
    arr.push_back("zuiqkeegs");
    arr.push_back("cat");
    arr.push_back("act");
    arr.push_back("tca");

    // utility function for storing
    // strings into hashmap
    storeInMap(arr);
    return 0;
}

Python3

# Python3 program for finding all anagram
# pairs in the given array
from collections import defaultdict

# Utility function for
# printing anagram list
def printAnagram(store: dict) -> None:

    for (k, v) in store.items():
        temp_vec = v
        size = len(temp_vec)

        if (size > 1):
            for i in range(size):
                print(temp_vec[i], end = " ")

            print()

# Utility function for storing
# the vector of strings into HashMap
def storeInMap(vec: list) -> None:

    store = defaultdict(lambda: list)

    for i in range(len(vec)):
        tempString = vec[i]
        tempString = ''.join(sorted(tempString))

        # Check for sorted string
        # if it already exists
        if (tempString not in store):
            temp_vec = []
            temp_vec.append(vec[i])
            store[tempString] = temp_vec

        else:

            # Push new string to
            # already existing key
            temp_vec = store[tempString]
            temp_vec.append(vec[i])
            store[tempString] = temp_vec

    # Print utility function for
    # printing all the anagrams
    printAnagram(store)

# Driver code
if __name__ == "__main__":

    # Initialize vector of strings
    arr = []
    arr.append("geeksquiz")
    arr.append("geeksforgeeks")
    arr.append("abcd")
    arr.append("forgeeksgeeks")
    arr.append("zuiqkeegs")
    arr.append("cat")
    arr.append("act")
    arr.append("tca")

    # Utility function for storing
    # strings into hashmap
    storeInMap(arr)

# This code is contributed by sanjeev2552

Java

import java.util.*;

public class Anagram {

    // Utility function for
    // printing anagram list
    public static void printAnagram(Map<String, List<String>> store) {
        for (Map.Entry<String, List<String>> entry : store.entrySet()) {
            List<String> tempVec = entry.getValue();
            int size = tempVec.size();

            for (int i = 0; i < size; i++)
                System.out.print(tempVec.get(i) + " ");

            System.out.println();
        }
    }

    // Utility function for storing
    // the list of strings into HashMap
    public static void storeInMap(List<String> arr) {
        Map<String, List<String>> store = new HashMap<>();

        for (int i = 0; i < arr.size(); i++) {
            String tempString = arr.get(i);

            // sort the string
            char[] tempArr = tempString.toCharArray();
            Arrays.sort(tempArr);
            tempString = new String(tempArr);

            // make hash of a sorted string
            if (!store.containsKey(tempString))
                store.put(tempString, new ArrayList<>());
            store.get(tempString).add(arr.get(i));
        }

        // print utility function for printing
        // all the anagrams
        printAnagram(store);
    }

    // Driver code
    public static void main(String[] args) {
        // initialize list of strings
        List<String> arr = new ArrayList<>();
        arr.add("geeksquiz");
        arr.add("geeksforgeeks");
        arr.add("abcd");
        arr.add("forgeeksgeeks");
        arr.add("zuiqkeegs");
        arr.add("cat");
        arr.add("act");
        arr.add("tca");

        // utility function for storing
        // strings into hashmap
        storeInMap(arr);
    }
}
// this code is added by devendra

C#

using System;
using System.Collections.Generic;

class Anagram {
    // Utility function for
    // printing anagram list
    public static void
    printAnagram(Dictionary<string, List<string> > store)
    {
        foreach(KeyValuePair<string, List<string> > entry in
                    store)
        {
            List<string> tempVec = entry.Value;
            int size = tempVec.Count;

            for (int i = 0; i < size; i++)
                Console.Write(tempVec[i] + " ");

            Console.WriteLine();
        }
    }

    // Utility function for storing
    // the list of strings into Dictionary
    public static void storeInMap(List<string> arr)
    {
        Dictionary<string, List<string> > store
            = new Dictionary<string, List<string> >();

        for (int i = 0; i < arr.Count; i++) {
            string tempString = arr[i];

            // sort the string
            char[] tempArr = tempString.ToCharArray();
            Array.Sort(tempArr);
            tempString = new string(tempArr);

            // make hash of a sorted string
            if (!store.ContainsKey(tempString))
                store[tempString] = new List<string>();
            store[tempString].Add(arr[i]);
        }

        // print utility function for printing
        // all the anagrams
        printAnagram(store);
    }

    // Driver code
    public static void Main(string[] args)
    {
        // initialize list of strings
        List<string> arr = new List<string>();
        arr.Add("geeksquiz");
        arr.Add("geeksforgeeks");
        arr.Add("abcd");
        arr.Add("forgeeksgeeks");
        arr.Add("zuiqkeegs");
        arr.Add("cat");
        arr.Add("act");
        arr.Add("tca");

        // utility function for storing
        // strings into dictionary
        storeInMap(arr);
    }
}
// This code is contributed by prajwal kandekar

Javascript

// Utility function for printing anagram list
function printAnagram(store) {
    for (let entry of Object.entries(store)) {
        let tempVec = entry[1];
        let size = tempVec.length;
        for (let i = 0; i < size; i++)
        console.log(tempVec[i]);
        console.log("");
    }
}

// Utility function for storing the list of strings into Dictionary
function storeInMap(arr) {
    let store = {};
    for (let i = 0; i < arr.length; i++) {
        let tempString = arr[i];

        // sort the string
        let tempArr = tempString.split("");
        tempArr.sort();
        tempString = tempArr.join("");

        // make hash of a sorted string
        if (!(tempString in store))
            store[tempString] = [];
        store[tempString].push(arr[i]);
    }

    // print utility function for printing
    // all the anagrams
    printAnagram(store);
}

// Driver code
function main() {
    // initialize list of strings
    let arr = [];
    arr.push("geeksquiz");
    arr.push("geeksforgeeks");
    arr.push("abcd");
    arr.push("forgeeksgeeks");
    arr.push("zuiqkeegs");
    arr.push("cat");
    arr.push("act");
    arr.push("tca");

    // utility function for storing
    // strings into dictionary
    storeInMap(arr);
}

main();

//This code is contributed by NarasingaNikhil

Output

cat act tca 
abcd 
geeksforgeeks forgeeksgeeks 
geeksquiz zuiqkeegs 

Note: Compile above program with -std=c++11 flag in g++ 

Complexity Analysis:

• Time Complexity: O(n * m(log m)),  where m is the length of a word.
  A single traversal through the array is needed.
• Space Complexity: O(n). 
  There are n words in a string. The map requires O(n) space to store the strings.

Another Approach: This program is designed to group anagrams from a given array of strings. The approach taken in this program is as follows:

1. Define a function storeInMap that takes a vector of strings as input and creates an unordered_map object to store the anagrams.
2. Iterate through each string in the vector and count the frequency of each character in the string.
3. Generate a hash string based on the frequency of characters for each string.
4. Insert the string into the unordered_map object using the hash string as the key.
5. Define another function printAnagram that takes an unordered_map object as input and prints the anagrams.
6. Iterate through the unordered_map object and print the anagrams using the values associated with each key.
7. In the main function, create a vector of strings containing the input data and call the storeInMap function to group the anagrams.

Implementation:

C++

#include <iostream>
#include <unordered_map>
#include <vector>
using namespace std;

void printAnagram(unordered_map<string, vector<string>>& store) {
    for (auto it : store) {
        vector<string> temp_vec(it.second);
        int size = temp_vec.size();

        for (int i = 0; i < size; i++)
            cout << temp_vec[i] << " ";

        cout << "\n";
    }
}

void storeInMap(vector<string>& vec) {
    unordered_map<string, vector<string>> store;

    for (int i = 0; i < vec.size(); i++) {
        string tempString(vec[i]);
        int charCount[26] = {0};

        // count the frequency of each character in the string
        for (char c : tempString) {
            charCount++;
        }

        // generate a hash string based on the frequency of characters
        string hashStr = "";
        for (int j = 0; j < 26; j++) {
            hashStr += to_string(charCount[j]);
            hashStr += "#";
        }

        // insert the string into the hashmap
        store[hashStr].push_back(vec[i]);
    }

    // print all the anagrams
    printAnagram(store);
}

int main() {
    vector<string> arr = {"geeksquiz", "geeksforgeeks", "abcd", "forgeeksgeeks", "zuiqkeegs", "cat", "act", "tca"};

    storeInMap(arr);
    return 0;
}
// This code is contributed by rudra1807raj

Java

// Java program to print anagrams together

import java.io.*;
import java.util.*;

class GFG {
  public static List<List<String>> Anagrams(String[] string_list)
    {

        HashMap <String, List<String>> mp = new HashMap<>();
        List<List<String>> ans = new ArrayList<>();

        for(String i: string_list)
        {
            char ch[] = i.toCharArray();
            Arrays.sort(ch);

            String s = String.valueOf(ch);

            if(mp.containsKey(s))
            {
                mp.get(s).add(i);
            }
            else
            {
                List<String> li = new ArrayList<>();
                li.add(i);

                mp.put(s,li);
            }
        }
        for(List<String> list: mp.values())
        ans.add(list);

        return ans;
    }
    public static void main (String[] args) {
        String arr[] = {"geeksquiz", "geeksforgeeks", "abcd", "forgeeksgeeks", "zuiqkeegs", "cat", "act", "tca"};
          System.out.println(Anagrams(arr));
    }
}
// This code is contributed by Raunak Singh

Python3

from collections import defaultdict

def print_anagram(store):
    for key, value in store.items():
        print(*value)

def store_in_map(arr):
    store = defaultdict(list)
    for string in arr:
        char_count = [0] * 26
        for c in string:
          #count the frequency of each character in the string
            char_count[ord(c) - ord('a')] += 1
        hash_str = '#'.join(map(str, char_count))
        store[hash_str].append(string)
        # print all the anagrams
    print_anagram(store)

if __name__ == '__main__':
    arr = ["geeksquiz", "geeksforgeeks", "abcd", "forgeeksgeeks", "zuiqkeegs", "cat", "act", "tca"]
    store_in_map(arr)

    #This code is contributed by NarasingaNikhil

C#

using System;
using System.Collections.Generic;

class Program
{
static void PrintAnagram(Dictionary<string, List<string>> store)
{
foreach (KeyValuePair<string, List<string>> pair in store)
{
List<string> tempVec = pair.Value;
int size = tempVec.Count;
          for (int i = 0; i < size; i++)
            Console.Write(tempVec[i] + " ");

        Console.WriteLine();
    }
}

static void StoreInMap(List<string> vec)
{
    Dictionary<string, List<string>> store = new Dictionary<string, List<string>>();

    for (int i = 0; i < vec.Count; i++)
    {
        string tempString = vec[i];
        int[] charCount = new int[26];

        // count the frequency of each character in the string
        foreach (char c in tempString)
        {
            charCount++;
        }

        // generate a hash string based on the frequency of characters
        string hashStr = "";
        for (int j = 0; j < 26; j++)
        {
            hashStr += charCount[j].ToString();
            hashStr += "#";
        }

        // insert the string into the hashmap
        if (store.ContainsKey(hashStr))
        {
            store[hashStr].Add(vec[i]);
        }
        else
        {
            store[hashStr] = new List<string>();
            store[hashStr].Add(vec[i]);
        }
    }

    // print all the anagrams
    PrintAnagram(store);
}

static void Main()
{
    List<string> arr = new List<string> { "geeksquiz", "geeksforgeeks", "abcd", "forgeeksgeeks", "zuiqkeegs", "cat", "act", "tca" };

    StoreInMap(arr);
}
}

Output

cat act tca 
abcd 
geeksforgeeks forgeeksgeeks 
geeksquiz zuiqkeegs 

Time Complexity: The time complexity of this code is O(n*m), where n is the number of strings in the given vector and m is the length of the longest string.
Auxiliary Space: The space complexity of this code is also O(n*m) because we are storing all the strings in the given vector in the store map.

This article is contributed by Mandeep Singh. If you like GeeksforGeeks and would like to contribute, you can also write an article using write.geeksforgeeks.org or mail your article to review-team@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.