Queue Operations
Given N integers, the task is to insert those elements in the queue. Also, given M integers, the task is to find the frequency of each number in the Queue.
Examples:
Input:
N = 8
1 2 3 4 5 2 3 1 (N integers)
M = 5
1 3 2 9 10 (M integers)
Output:
2 2 2 -1 -1Explanation:
After inserting 1, 2, 3, 4, 5, 2, 3, 1 into the queue, frequency of 1 is 2, 3 is 2, 2 is 2, 9 is -1 and 10 is -1 (since, 9 and 10 is not there in the queue).Input:
N = 5
5 2 2 4 5 (N integers)
M = 5
2 3 4 5 1 (M integers)
Output:
2 -1 1 2 -1
Approach: The given problem can be solved by using a simple queue. The idea is to insert N integers one by one into the queue and then check the frequency of M integers. Separate functions will be created to perform both operations. Follow the steps below to solve the problem.
- Create a queue and push all given integers into the queue.
- After pushing all the elements into the queue create another function for counting the frequency of given M elements one by one.
- Take a variable cntFrequency to keep track of frequency of current element.
- Pop all the elements from queue till its size and each time check if current element in queue is equal to element for which we are checking for frequency.
– if both are equal, increment cntFrequency by 1
– else, do nothing. - Push the current element back to the queue so that for next case queue will not get disturbed.
- Print the frequency of each element found.
Below is the implementation of the above approach:
Java
// Java Program to implement above approachimport java.io.*;import java.util.*;class GFG { // Driver code public static void main(String[] args) { // Declaring Queue Queue<Integer> q = new LinkedList<>(); int N = 8; int[] a = new int[] { 1, 2, 3, 4, 5, 2, 3, 1 }; int M = 5; int[] b = new int[] { 1, 3, 2, 9, 10 }; // Invoking object of Geeks class Geeks obj = new Geeks(); for (int i = 0; i < N; i++) { // calling insert() // to add elements in queue obj.insert(q, a[i]); } for (int i = 0; i < M; i++) { // calling findFrequency() int f = obj.findFrequency(q, b[i]); if (f != 0) { // variable f // will have final frequency System.out.print(f + " "); } else { System.out.print("-1" + " "); } } }}// Helper class Geeks to implement// insert() and findFrequency()class Geeks { // Function to insert // element into the queue static void insert(Queue<Integer> q, int k) { // adding N integers into the Queue q.add(k); } // Function to find frequency of an element // return the frequency of k static int findFrequency(Queue<Integer> q, int k) { // to count frequency of elements int cntFrequency = 0; // storing size of queue in a variable int size = q.size(); // running loop untill size becomes zero while (size-- != 0) { // storing and deleting // first element from queue int x = q.poll(); // comparing if it's equal to integer K // that belongs to M if (x == k) { // increament count cntFrequency++; } // add element back to queue because // we also want N integers q.add(x); } // return the count return cntFrequency; }} |
Python3
# Python Program to implement above approachimport collections# Helper class Geeks to implement# insert() and findFrequency()class Geeks: # Function to insert # element into the queue def insert(self, q, k): # adding N integers into the Queue q.append(k) # Function to find frequency of an element # return the frequency of k def findFrequency(self, q, k): # to count frequency of elements cntFrequency = 0 # storing size of queue in a variable size = len(q) # running loop untill size becomes zero while (size): size = size - 1 # storing and deleting # first element from queue x = q.popleft() # comparing if it's equal to integer K # that belongs to M if (x == k): # increament count cntFrequency += 1 # add element back to queue because # we also want N integers q.append(x) # return the count return cntFrequency# Declaring Queueq = collections.deque()N = 8a = [1, 2, 3, 4, 5, 2, 3, 1]M = 5b = [1, 3, 2, 9, 10]# Invoking object of Geeks classobj = Geeks()for i in range(N): # calling insert() # to add elements in queue obj.insert(q, a[i])for i in range(M): # calling findFrequency() f = obj.findFrequency(q, b[i]) if (f != 0): # variable f # will have final frequency print(f, end=" ") else: print("-1", end=" ")print(" ")# This code is contributed by gfgking. |
C#
// C# Program to implement above approachusing System;using System.Collections.Generic;public class GFG { // Helper class Geeks to implement// insert() and findFrequency()public class Geeks { // Function to insert // element into the queue public void insert(Queue<int> q, int k) { // adding N integers into the Queue q.Enqueue(k); } // Function to find frequency of an element // return the frequency of k public int findFrequency(Queue<int> q, int k) { // to count frequency of elements int cntFrequency = 0; // storing size of queue in a variable int size = q.Count; // running loop untill size becomes zero while (size-- != 0) { // storing and deleting // first element from queue int x = q.Peek(); q.Dequeue(); // comparing if it's equal to integer K // that belongs to M if (x == k) { // increament count cntFrequency++; } // add element back to queue because // we also want N integers q.Enqueue(x); } // return the count return cntFrequency; }} // Driver code public static void Main() { // Declaring Queue Queue<int> q = new Queue<int>(); int N = 8; int[] a = new int[] { 1, 2, 3, 4, 5, 2, 3, 1 }; int M = 5; int[] b = new int[] { 1, 3, 2, 9, 10 }; // Invoking object of Geeks class Geeks obj = new Geeks(); for (int i = 0; i < N; i++) { // calling insert() // to add elements in queue obj.insert(q, a[i]); } for (int i = 0; i < M; i++) { // calling findFrequency() int f = obj.findFrequency(q, b[i]); if (f != 0) { // variable f // will have final frequency Console.Write(f + " "); } else { Console.Write("-1" + " "); } } }}// This code is contributed by SURENDRA_GANGWAR. |
2 2 2 -1 -1
Time Complexity: O(N*M)
Auxiliary Space: O(N)
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