Merge two Maps of Array into one sorted Map of Array
Last Updated :
24 Feb, 2023
Given two maps map1 and map2 having a string as the key and arrays of integers as values, the task is to merge them in one map such that if a key is common in both the maps, the respective arrays should be merged.
Examples:
Input: map1 = { ("key1", {0, 1}), ("key2", {0, 1}) }, map2 = { ("key2", {1, 2}) };
Output: { (key1, {0, 1}), (key2, {0, 1, 2}) }
Explanation: After merging key1 array will become {0, 1} and for key2 after merging array will become {0, 1, 2}
Input: map1 = {("key1", {0, 1})}, map2 = {("key2", {1, 2})};
Output: {(key1, [0, 1]), (key2, [1, 2])}
Approach: The solution to the problem is based on the concept of merging two arrays. Follow the steps mentioned below:
- Create a map to store the merged maps
- Traverse map1 and store all the key-value pairs in map1.
- Traverse map2 and:
- If the key of map2 does not exists in map1, just insert this key value pair in map1
- If the key of map2 exists in map1,
- Take the array of map1 and array of map2
- Sort both the arrays, and
- Merge them using approach mentioned in merge two arrays.
- Return the map3 at the end.
Below is the implementation of the above approach.
C++
// C++ code to implement the approach
#include <bits/stdc++.h>
using namespace std;
// Function to merge arrays
vector<int> mergeArrays(vector<int>& a, vector<int>& b,
int n, int m)
{
vector<int> mergedArray;
// Declaring a map.
// Using map as a inbuilt tool
// to store elements in sorted order.
map<int, bool> mp;
// Inserting values to a map.
for (int i = 0; i < n; i++)
mp[a[i]] = true;
for (int i = 0; i < m; i++)
mp[b[i]] = true;
// Printing keys of the map.
for (auto i : mp)
mergedArray.push_back(i.first);
return mergedArray;
}
// Function to merge maps
map<string, vector<int> >
mergeMap(map<string, vector<int> >& map1,
map<string, vector<int> >& map2)
{
map<string, vector<int> > map3;
map3.insert(map1.begin(), map1.end());
for (auto itr : map2) {
if (map3.find(itr.first) == map3.end())
map3.insert({ itr.first, itr.second });
else {
auto temp_itr = map3.find(itr.first);
vector<int> arr = mergeArrays(
itr.second, temp_itr->second,
itr.second.size(),
temp_itr->second.size());
map3[itr.first] = arr;
}
}
return map3;
}
// Driver code
int main()
{
map<string, vector<int> > map1, map2, map3;
map1.insert({ "key1", { 0, 1 } });
map1.insert({ "key2", { 0, 1 } });
map2.insert({ "key2", { 1, 2 } });
// Function call
map3 = mergeMap(map1, map2);
for (auto itr : map3) {
cout << "\"" << itr.first << "\", { ";
for (auto x : itr.second)
cout << x << " ";
cout << "}\n";
}
return 0;
}
/*package whatever //do not write package name here */
import java.util.*;
class GFG {
public static Vector<Integer> mergeArrays(Vector<Integer> a,
Vector<Integer> b, int n, int m) {
Vector<Integer> mergedArray = new Vector<Integer>();
// Declaring a map.
// Using map as a inbuilt tool
// to store elements in sorted order.
Map<Integer, Boolean> mp = new HashMap<Integer, Boolean>();
// Inserting values to a map.
for (int i = 0; i < n; i++)
mp.put(a.get(i), true);
for (int i = 0; i < m; i++)
mp.put(b.get(i), true);
// Printing keys of the map.
for (Map.Entry<Integer, Boolean> i : mp.entrySet())
mergedArray.add(i.getKey());
return mergedArray;
}
public static Map<String, Vector<Integer>> mergeMap(Map<String,
Vector<Integer>> map1, Map<String, Vector<Integer>> map2) {
Map<String, Vector<Integer>> map3 = new HashMap<String, Vector<Integer>>();
map3.putAll(map1);
for (Map.Entry<String, Vector<Integer>> itr : map2.entrySet()) {
if (!map3.containsKey(itr.getKey()))
map3.put(itr.getKey(), itr.getValue());
else {
Vector<Integer> temp_itr = map3.get(itr.getKey());
Vector<Integer> arr = mergeArrays(itr.getValue(),
temp_itr, itr.getValue().size(), temp_itr.size());
map3.put(itr.getKey(), arr);
}
}
return map3;
}
public static void main(String[] args) {
Map<String, Vector<Integer>> map1 = new HashMap<String, Vector<Integer>>();
Map<String, Vector<Integer>> map2 = new HashMap<String, Vector<Integer>>();
Map<String, Vector<Integer>> map3 = new HashMap<String, Vector<Integer>>();
map1.put("key1", new Vector<Integer>(Arrays.asList(0, 1)));
map1.put("key2", new Vector<Integer>(Arrays.asList(0, 1)));
map2.put("key2", new Vector<Integer>(Arrays.asList(1, 2)));
map3 = mergeMap(map1, map2);
for (Map.Entry<String, Vector<Integer>> itr : map3.entrySet()) {
System.out.print("\"" + itr.getKey() + "\", { ");
for (int x : itr.getValue())
System.out.print(x + " ");
System.out.println("}");
}
}
}
# Python code to implement the approach
# Function to merge arrays
def mergeArrays (a, b, n, m):
mergedArray = [];
# Declaring a map.
# Using map as a inbuilt tool
# to store elements in sorted order.
mp = {};
# Inserting values to a map.
for i in range(n):
mp[a[i]] = True;
for i in range(m):
mp[b[i]] = True;
# Printing keys of the map.
for i in mp:
mergedArray.append(i);
return mergedArray;
# Function to merge maps
def mergeMap (map1, map2):
map3 = {};
for itm in map1.keys():
map3[itm] = map1[itm];
for itr in map2.keys():
if (not itr in map3.keys()):
map3[itr] = map2[itr];
else:
arr = mergeArrays(map2[itr], map3[itr], len(map2[itr]), len(map3[itr]));
map3[itr] = arr;
return map3;
# Driver code
map1 = {}
map2 = {}
map3 = {};
map1["key1"] = [0, 1];
map1["key2"] = [0, 1];
map2["key2"] = [1, 2];
# Function call
map3 = mergeMap(map1, map2);
for itr in map3.keys():
print(f"\"{itr}\", {{", end=" ")
map3[itr].sort()
for x in map3[itr]:
print(map3[itr][x], end=" ");
print("} ");
# This code is contributed by Saurabh Jaiswal
<script>
// JavaScript code to implement the approach
// Function to merge arrays
const mergeArrays = (a, b, n, m) => {
let mergedArray = [];
// Declaring a map.
// Using map as a inbuilt tool
// to store elements in sorted order.
let mp = {};
// Inserting values to a map.
for (let i = 0; i < n; i++)
mp[a[i]] = true;
for (let i = 0; i < m; i++)
mp[b[i]] = true;
// Printing keys of the map.
for (let i in mp)
mergedArray.push(i);
return mergedArray;
}
// Function to merge maps
const mergeMap = (map1, map2) => {
let map3 = {};
for (let itm in map1) map3[itm] = map1[itm];
for (let itr in map2) {
if (!(itr in map3))
map3[itr] = map2[itr];
else {
let arr = mergeArrays(map2[itr], map3[itr], map2[itr].length, map3[itr].length);
map3[itr] = arr;
}
}
return map3;
}
// Driver code
let map1 = {}, map2 = {}, map3 = {};
map1["key1"] = [0, 1];
map1["key2"] = [0, 1];
map2["key2"] = [1, 2];
// Function call
map3 = mergeMap(map1, map2);
for (let itr in map3) {
document.write(`"${itr}", { `);
for (let x in map3[itr])
document.write(`${map3[itr][x]} `);
document.write("}<br/>");
}
// This code is contributed by rakeshsahni
</script>
// C# code to implement the approach
using System;
using System.Collections.Generic;
namespace MergeMaps
{
class Program
{
// Function to merge arrays
static List<int> MergeArrays(List<int> a, List<int> b, int n, int m)
{
List<int> mergedArray = new List<int>();
// Declaring a dictionary
Dictionary<int, bool> dict = new Dictionary<int, bool>();
// Inserting values to a dictionary
foreach (int i in a)
dict[i] = true;
foreach (int i in b)
dict[i] = true;
// Printing keys of the dictionary
foreach (var i in dict.Keys)
mergedArray.Add(i);
return mergedArray;
}
// Function to merge dictionaries
static Dictionary<string, List<int>> MergeMap(Dictionary<string, List<int>> map1, Dictionary<string, List<int>> map2)
{
Dictionary<string, List<int>> map3 = new Dictionary<string, List<int>>();
foreach (var item in map1)
map3[item.Key] = item.Value;
foreach (var itr in map2)
{
if (!map3.ContainsKey(itr.Key))
map3[itr.Key] = itr.Value;
else
{
var temp_itr = map3[itr.Key];
List<int> arr = MergeArrays(itr.Value, temp_itr, itr.Value.Count, temp_itr.Count);
map3[itr.Key] = arr;
}
}
return map3;
}
static void Main(string[] args)
{
Dictionary<string, List<int>> map1 = new Dictionary<string, List<int>>();
Dictionary<string, List<int>> map2 = new Dictionary<string, List<int>>();
Dictionary<string, List<int>> map3 = new Dictionary<string, List<int>>();
map1["key1"] = new List<int> { 0, 1 };
map1["key2"] = new List<int> { 0, 1 };
map2["key2"] = new List<int> { 1, 2 };
// Function call
map3 = MergeMap(map1, map2);
foreach (var itr in map3)
{
Console.Write("\"" + itr.Key + "\", { ");
foreach (var x in itr.Value)
Console.Write(x + " ");
Console.WriteLine("}");
}
}
}
}
Output"key1", { 0 1 }
"key2", { 0 1 2 }
Time Complexity: O(N * log N + M * log M)
Auxiliary Space: O(M + N
C++
// C++ code to implement the approach
#include <bits/stdc++.h>
using namespace std;
// Function to merge arrays
vector<int> mergeArrays(vector<int>& a, vector<int>& b,
int n, int m)
{
vector<int> mergedArray;
// Declaring a map.
// Using map as a inbuilt tool
// to store elements in sorted order.
map<int, bool> mp;
// Inserting values to a map.
for (int i = 0; i < n; i++)
mp[a[i]] = true;
for (int i = 0; i < m; i++)
mp[b[i]] = true;
// Printing keys of the map.
for (auto i : mp)
mergedArray.push_back(i.first);
return mergedArray;
}
// Function to merge maps
map<string, vector<int> >
mergeMap(map<string, vector<int> >& map1,
map<string, vector<int> >& map2)
{
map<string, vector<int> > map3;
map3.insert(map1.begin(), map1.end());
for (auto itr : map2) {
if (map3.find(itr.first) == map3.end())
map3.insert({ itr.first, itr.second });
else {
auto temp_itr = map3.find(itr.first);
vector<int> arr = mergeArrays(
itr.second, temp_itr->second,
itr.second.size(), temp_itr->second.size());
map3[itr.first] = arr;
}
}
return map3;
}
// Driver code
int main()
{
map<string, vector<int> > map1, map2, map3;
map1.insert({ "key1", { 0, 1 } });
map1.insert({ "key2", { 0, 1 } });
map2.insert({ "key2", { 1, 2 } });
// Function call
map3 = mergeMap(map1, map2);
for (auto itr : map3) {
cout << "\"" << itr.first << "\", { ";
for (auto x : itr.second)
cout << x << " ";
cout << "}\n";
}
return 0;
}
/*package whatever //do not write package name here */
import java.util.*;
class GFG {
public static Vector<Integer> mergeArrays(Vector<Integer> a,
Vector<Integer> b, int n, int m) {
Vector<Integer> mergedArray = new Vector<Integer>();
// Declaring a map.
// Using map as a inbuilt tool
// to store elements in sorted order.
Map<Integer, Boolean> mp = new HashMap<Integer, Boolean>();
// Inserting values to a map.
for (int i = 0; i < n; i++)
mp.put(a.get(i), true);
for (int i = 0; i < m; i++)
mp.put(b.get(i), true);
// Printing keys of the map.
for (Map.Entry<Integer, Boolean> i : mp.entrySet())
mergedArray.add(i.getKey());
return mergedArray;
}
public static Map<String, Vector<Integer>> mergeMap(Map<String,
Vector<Integer>> map1, Map<String, Vector<Integer>> map2) {
Map<String, Vector<Integer>> map3 = new HashMap<String, Vector<Integer>>();
map3.putAll(map1);
for (Map.Entry<String, Vector<Integer>> itr : map2.entrySet()) {
if (!map3.containsKey(itr.getKey()))
map3.put(itr.getKey(), itr.getValue());
else {
Vector<Integer> temp_itr = map3.get(itr.getKey());
Vector<Integer> arr = mergeArrays(itr.getValue(),
temp_itr, itr.getValue().size(), temp_itr.size());
map3.put(itr.getKey(), arr);
}
}
return map3;
}
public static void main(String[] args) {
Map<String, Vector<Integer>> map1 = new HashMap<String, Vector<Integer>>();
Map<String, Vector<Integer>> map2 = new HashMap<String, Vector<Integer>>();
Map<String, Vector<Integer>> map3 = new HashMap<String, Vector<Integer>>();
map1.put("key1", new Vector<Integer>(Arrays.asList(0, 1)));
map1.put("key2", new Vector<Integer>(Arrays.asList(0, 1)));
map2.put("key2", new Vector<Integer>(Arrays.asList(1, 2)));
map3 = mergeMap(map1, map2);
for (Map.Entry<String, Vector<Integer>> itr : map3.entrySet()) {
System.out.print("\"" + itr.getKey() + "\", { ");
for (int x : itr.getValue())
System.out.print(x + " ");
System.out.println("}");
}
}
}
# Python code to implement the approach
# Function to merge arrays
def mergeArrays (a, b, n, m):
mergedArray = [];
# Declaring a map.
# Using map as a inbuilt tool
# to store elements in sorted order.
mp = {};
# Inserting values to a map.
for i in range(n):
mp[a[i]] = True;
for i in range(m):
mp[b[i]] = True;
# Printing keys of the map.
for i in mp:
mergedArray.append(i);
return mergedArray;
# Function to merge maps
def mergeMap (map1, map2):
map3 = {};
for itm in map1.keys():
map3[itm] = map1[itm];
for itr in map2.keys():
if (not itr in map3.keys()):
map3[itr] = map2[itr];
else:
arr = mergeArrays(map2[itr], map3[itr], len(map2[itr]), len(map3[itr]));
map3[itr] = arr;
return map3;
# Driver code
map1 = {}
map2 = {}
map3 = {};
map1["key1"] = [0, 1];
map1["key2"] = [0, 1];
map2["key2"] = [1, 2];
# Function call
map3 = mergeMap(map1, map2);
for itr in map3.keys():
print(f"\"{itr}\", {{", end=" ")
map3[itr].sort()
for x in map3[itr]:
print(map3[itr][x], end=" ");
print("} ");
# This code is contributed by Saurabh Jaiswal
<script>
// JavaScript code to implement the approach
// Function to merge arrays
const mergeArrays = (a, b, n, m) => {
let mergedArray = [];
// Declaring a map.
// Using map as a inbuilt tool
// to store elements in sorted order.
let mp = {};
// Inserting values to a map.
for (let i = 0; i < n; i++)
mp[a[i]] = true;
for (let i = 0; i < m; i++)
mp[b[i]] = true;
// Printing keys of the map.
for (let i in mp)
mergedArray.push(i);
return mergedArray;
}
// Function to merge maps
const mergeMap = (map1, map2) => {
let map3 = {};
for (let itm in map1) map3[itm] = map1[itm];
for (let itr in map2) {
if (!(itr in map3))
map3[itr] = map2[itr];
else {
let arr = mergeArrays(map2[itr], map3[itr], map2[itr].length, map3[itr].length);
map3[itr] = arr;
}
}
return map3;
}
// Driver code
let map1 = {}, map2 = {}, map3 = {};
map1["key1"] = [0, 1];
map1["key2"] = [0, 1];
map2["key2"] = [1, 2];
// Function call
map3 = mergeMap(map1, map2);
for (let itr in map3) {
document.write(`"${itr}", { `);
for (let x in map3[itr])
document.write(`${map3[itr][x]} `);
document.write("}<br/>");
}
// This code is contributed by rakeshsahni
</script>
// C# code to implement the approach
using System;
using System.Collections.Generic;
namespace MergeMaps
{
class Program
{
// Function to merge arrays
static List<int> MergeArrays(List<int> a, List<int> b, int n, int m)
{
List<int> mergedArray = new List<int>();
// Declaring a dictionary
Dictionary<int, bool> dict = new Dictionary<int, bool>();
// Inserting values to a dictionary
foreach (int i in a)
dict[i] = true;
foreach (int i in b)
dict[i] = true;
// Printing keys of the dictionary
foreach (var i in dict.Keys)
mergedArray.Add(i);
return mergedArray;
}
// Function to merge dictionaries
static Dictionary<string, List<int>> MergeMap(Dictionary<string, List<int>> map1, Dictionary<string, List<int>> map2)
{
Dictionary<string, List<int>> map3 = new Dictionary<string, List<int>>();
foreach (var item in map1)
map3[item.Key] = item.Value;
foreach (var itr in map2)
{
if (!map3.ContainsKey(itr.Key))
map3[itr.Key] = itr.Value;
else
{
var temp_itr = map3[itr.Key];
List<int> arr = MergeArrays(itr.Value, temp_itr, itr.Value.Count, temp_itr.Count);
map3[itr.Key] = arr;
}
}
return map3;
}
static void Main(string[] args)
{
Dictionary<string, List<int>> map1 = new Dictionary<string, List<int>>();
Dictionary<string, List<int>> map2 = new Dictionary<string, List<int>>();
Dictionary<string, List<int>> map3 = new Dictionary<string, List<int>>();
map1["key1"] = new List<int> { 0, 1 };
map1["key2"] = new List<int> { 0, 1 };
map2["key2"] = new List<int> { 1, 2 };
// Function call
map3 = MergeMap(map1, map2);
foreach (var itr in map3)
{
Console.Write("\"" + itr.Key + "\", { ");
foreach (var x in itr.Value)
Console.Write(x + " ");
Console.WriteLine("}");
}
}
}
}
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