Check if Queue Elements are pairwise consecutive | Set-2
Given a Queue of integers. The task is to check if consecutive elements in the queue are pairwise consecutive.
Examples:
Input: 1 2 5 6 9 10 Output: Yes Input: 2 3 9 11 8 7 Output: No
Approach :
- Take a variable n to store size of queue.
- Push an element to the queue which acts as marker.
- Now, If size of queue is odd, start popping a pair while n > 2. Also, while popping these pairs, check for their difference and decrease n by 2, if there difference is not equal to 1, set flag to false.
- If size of queue is even, start popping a pair while n > 1. Also, while popping these pairs, check for their difference and decrease n by 2, if their difference is not equal to 1, set flag to false.
- Finally, check flag, if it is true, it means elements in the queue are pairwise sorted, else not.
Below is the implementation of above approach:
C++
// C++ program to check if successive // pair of numbers in the queue are // consecutive or not #include <bits/stdc++.h> using namespace std; // Function to check if elements are // pairwise consecutive in queue bool pairWiseConsecutive(queue<int> q) { // Fetching size of queue int n = q.size(); // Pushing extra element to the queue // which acts as marker q.push(INT_MIN); // Result flag bool result = true; // If number of elements in the // queue is odd pop elements while // its size is greater than 2. // Else, pop elements while its // size is greater than 1 if (n % 2 != 0) { while (n > 2) { int x = q.front(); q.pop(); q.push(x); n--; int y = q.front(); q.pop(); q.push(y); n--; if (abs(x - y) != 1) { result = false; } } // Popping the last element of queue // and pushing it again. // Also, popping the extra element // that we have pushed as marker q.push(q.front()); q.pop(); q.pop(); } else { while (n > 1) { int x = q.front(); q.pop(); q.push(x); n--; int y = q.front(); q.pop(); q.push(y); n--; if (abs(x - y) != 1) { result = false; } } // popping the extra element that // we have pushed as marker q.pop(); } return result; } // Driver program int main() { // Pushing elements into the queue queue<int> q; q.push(4); q.push(5); q.push(-2); q.push(-3); q.push(11); q.push(10); q.push(5); q.push(6); q.push(8); if (pairWiseConsecutive(q)) cout << "Yes" << endl; else cout << "No" << endl; return 0; } |
chevron_right
filter_none
Java
import java.util.LinkedList; import java.util.Queue; // Java program to check if successive // pair of numbers in the queue are // consecutive or not public class GFG { // Function to check if elements are // pairwise consecutive in queue static boolean pairWiseConsecutive(Queue<Integer> q) { // Fetching size of queue int n = q.size(); // Pushing extra element to the queue // which acts as marker q.add(Integer.MAX_VALUE); // Result flag boolean result = true; // If number of elements in the // queue is odd pop elements while // its size is greater than 2. // Else, pop elements while its // size is greater than 1 if (n % 2 != 0) { while (n > 2) { int x = q.peek(); q.remove(); q.add(x); n--; int y = q.peek(); q.remove(); q.add(y); n--; if (Math.abs(x - y) != 1) { result = false; } } // Popping the last element of queue // and pushing it again. // Also, popping the extra element // that we have pushed as marker q.add(q.peek()); q.remove(); q.remove(); } else { while (n > 1) { int x = q.peek(); q.remove(); q.add(x); n--; int y = q.peek(); q.remove(); q.add(y); n--; if (Math.abs(x - y) != 1) { result = false; } } // popping the extra element that // we have pushed as marker q.remove(); } return result; } // Driver program static public void main(String[] args) { // Pushing elements into the queue Queue<Integer> q = new LinkedList<>(); q.add(4); q.add(5); q.add(-2); q.add(-3); q.add(11); q.add(10); q.add(5); q.add(6); q.add(8); if (pairWiseConsecutive(q)) { System.out.println("Yes"); } else { System.out.println("No"); } } } // This code is contributed by Rajput-Ji |
chevron_right
filter_none
C#
// C# rogram to check if successive // pair of numbers in the queue are // consecutive or not using System; using System.Collections.Generic; class GFG { // Function to check if elements are // pairwise consecutive in queue static Boolean pairWiseConsecutive(Queue<int> q) { // Fetching size of queue int n = q.Count; // Pushing extra element to the queue // which acts as marker q.Enqueue(int.MaxValue); // Result flag Boolean result = true; // If number of elements in the // queue is odd pop elements while // its size is greater than 2. // Else, pop elements while its // size is greater than 1 if (n % 2 != 0) { while (n > 2) { int x = q.Peek(); q.Dequeue(); q.Enqueue(x); n--; int y = q.Peek(); q.Dequeue(); q.Enqueue(y); n--; if (Math.Abs(x - y) != 1) { result = false; } } // Popping the last element of queue // and pushing it again. // Also, popping the extra element // that we have pushed as marker q.Enqueue(q.Peek()); q.Dequeue(); q.Dequeue(); } else { while (n > 1) { int x = q.Peek(); q.Dequeue(); q.Enqueue(x); n--; int y = q.Peek(); q.Dequeue(); q.Enqueue(y); n--; if (Math.Abs(x - y) != 1) { result = false; } } // popping the extra element that // we have pushed as marker q.Dequeue(); } return result; } // Driver Code static public void Main(String[] args) { // Pushing elements into the queue Queue<int> q = new Queue<int>(); q.Enqueue(4); q.Enqueue(5); q.Enqueue(-2); q.Enqueue(-3); q.Enqueue(11); q.Enqueue(10); q.Enqueue(5); q.Enqueue(6); q.Enqueue(8); if (pairWiseConsecutive(q)) { Console.WriteLine("Yes"); } else { Console.WriteLine("No"); } } } // This code is contributed by Rajput-Ji |
chevron_right
filter_none
Output:
Yes
Time Complexity: O(n)
Auxiliary Space: O(1)
Recommended Posts:
- Check if Queue Elements are pairwise consecutive
- Modulus of all pairwise consecutive elements in an Array
- Check if the elements of stack are pairwise sorted
- Check if a queue can be sorted into another queue using a stack
- Reversing the first K elements of a Queue
- Check if moves in a stack or queue are possible or not
- Stack and Queue in Python using queue Module
- queue::front() and queue::back() in C++ STL
- Reversing a Queue using another Queue
- queue::push() and queue::pop() in C++ STL
- queue::emplace() in C++ STL
- Queue in Python
- Reversing a Queue
- Queue using Stacks
- queue::swap() in C++ STL
If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.
Please Improve this article if you find anything incorrect by clicking on the "Improve Article" button below.
Improved By : Rajput-Ji
