Sort an array of strings according to string lengths using Map

Given an array of strings, we need to sort the array in increasing order of string lengths, using Map Data Structure. Examples:

Input: str[] = {“GeeksforGeeeks”, “I”, “from”, “am”} Output: I am from GeeksforGeeks Input: str[] = {“You”, “are”, “beautiful”, “looking”} Output: You are looking beautiful

Approach: The given approach is for Java using TreeMap

• Take a TreeMap which will contain the length of the string as the key and an ArrayList of Strings that has the same length that of the key.
• Since we know that a TreeMap is already sorted so after inserting into the TreeMap we again fetch the values(the Strings from the ArrayList) one by one into the Strings Array.

Below is the implementation of the above approach: 

C++

// C++ program to sort an Array of
// Strings according to their lengths
// using Map
#include <bits/stdc++.h>
using namespace std;

// Function to Sort the array of string
// according to lengths using Map
vector<string> sortS(vector<string>& str, int n)
{
    map<int, vector<string> > m;
    for (int i = 0; i < n; i++) {
        m[str[i].length()].push_back(str[i]);
    }

    int temp = 0;
    for (auto i : m) {
        for (int j = 0; j < i.second.size(); j++) {
            str[temp] = i.second[j];
            temp++;
        }
    }

    return str;
}

// Function to print the sorted array of string
void printArraystring(vector<string> str, int n)
{
    for (int i = 0; i < n; i++)
        cout << str[i] << " ";
}

// Driver function
int main()
{
    vector<string> arr;
      arr = { "GeeksforGeeks", "I", "from", "am" };
    int n = arr.size();

    // Function to perform sorting
    arr = sortS(arr, n);

    // Calling the function to print result
    printArraystring(arr, n);
}

// This code is contributed by akashish__

Java

// Java program to sort an Array of
// Strings according to their lengths
// using Map

import java.util.*;
import java.util.Map.Entry;
import java.io.*;

public class GFG {

    // Function to Sort the array of string
    // according to lengths using Map
    static String[] sort(String[] str, int n)
    {
        TreeMap<Integer, ArrayList<String> > map
            = new TreeMap<Integer, ArrayList<String> >();

        for (int i = 0; i < n; i++) {

            map.putIfAbsent(str[i].length(),
                            new ArrayList<String>());
            map.get(str[i].length()).add(str[i]);
        }

        int temp = 0;

        for (Entry<Integer, ArrayList<String> >
                 e : map.entrySet()) {

            for (int i = 0; i < e.getValue().size(); i++) {

                str[temp] = e.getValue().get(i);
                temp++;
            }
        }
        return str;
    }

    // Function to print the sorted array of string
    static void printArraystring(String str[], int n)
    {
        for (int i = 0; i < n; i++)
            System.out.print(str[i] + " ");
    }

    // Driver function
    public static void main(String args[])
    {
        String[] arr = { "GeeksforGeeks",
                         "I", "from", "am" };
        int n = arr.length;

        // Function to perform sorting
        arr = sort(arr, n);

        // Calling the function to print result
        printArraystring(arr, n);
    }
}

Python3

from collections import defaultdict

# Function to Sort the array of string
# according to lengths using Map
def sort(str, n):
    map = defaultdict(list)

    for i in range(n):
        map[len(str[i])].append(str[i])

    return [val for key in sorted(map) for val in map[key]]

# Driver function
arr = ["GeeksforGeeks", "I", "from", "am"]
n = len(arr)

# Function to perform sorting
arr = sort(arr, n)

# Calling the function to print result
print(arr)

#  This code is contributed by akashish__

C#

using System;
using System.Collections.Generic;

using System.Linq;


public class GFG
{

    // Function to Sort the array of string
    // according to lengths using Map
    public static string[] sort(string[] str, int n)
    {
        var map = new SortedDictionary<int, List<string>>();

       for (int i = 0; i < n; i++)
        {
           map[str[i].Length] = new List<string>();
          }

        for (int i = 0; i < n; i++)
        {
            map[str[i].Length].Add(str[i]);
        }
         var temp = 0;
        foreach (KeyValuePair<int, List<string>> e in map)
        {

            for (int i = 0; i < e.Value.Count; i++)
            {
                str[temp] = e.Value[i];
                temp++;
            }
        }
        return str;
    }

    // Function to print the sorted array of string
    public static void printArraystring(string[] str, int n)
    {
        for (int i = 0; i < n; i++)
        {
            Console.Write(str[i] + " ");
        }
    }

    // Driver function
    public static void Main(string[] args)
    {
        string[] arr = {"GeeksforGeeks", "I", "from", "am"};
        var n = arr.Length;

        // Function to perform sorting
        arr = GFG.sort(arr, n);

        // Calling the function to print result
        GFG.printArraystring(arr, n);
    }
}

// This code is contributed by aadityaburujwale.

Javascript

// Function to Sort the array of string
// according to lengths using Map
function sort(str, n) {
    let map = new Map();

    for (let i = 0; i < n; i++) {
        let list = map.get(str[i].length);
        if (list === undefined) {
            list = [];
            list.push(str[i]);
            map.set(str[i].length, list);
        } else {
            list.push(str[i]);
            map.set(str[i].length, list);
        }
    }
    let sortedKeys = Array.from(map.keys()).sort((a, b) => a - b);
    let result = [];
    for (let key of sortedKeys) {
        result = result.concat(map.get(key));
    }
    return result;
}

// Driver function
let arr = ["GeeksforGeeks", "I", "from", "am"];
let n = arr.length;

// Function to perform sorting
arr = sort(arr, n);

// Calling the function to print result
console.log(arr);

// This code is contributed by akashish.

Output:

I am from GeeksforGeeks