Minimum number of consecutive sequences that can be formed in an array

Given an array of integers. The task is to find the minimum number of consecutive sequences that can be formed using the elements of the array.

Examples:

Input: arr[] = { -3, -2, -1, 0, 2 }
Output: 2
Consecutive sequences are (-3, -2, -1, 0), (2).

Input: arr[] = { 3, 4, 0, 2, 6, 5, 10 }
Output: 3
Consecutive sequences are (0), {2, 3, 4, 5, 6} and {10}


Approach:

  • Sort the array.
  • Iterate the array, and check if current element is just 1 smaller than the next element.
  • If it is then increment the count by 1.
  • Return the final count of consecutive sequences.

Below is the implementation of above approach :

C++

filter_none

edit
close

play_arrow

link
brightness_4
code

// C++ program find the minimum number of consecutive 
// sequences in an array
#include <bits/stdc++.h>
using namespace std;
  
int countSequences(int arr[], int n)
{
    int count = 1;
  
    sort(arr, arr + n);
  
    for (int i = 0; i < n - 1; i++)
        if (arr[i] + 1 != arr[i + 1])
            count++;
  
    return count;
}
  
// Driver program
int main()
{
    int arr[] = { 1, 7, 3, 5, 10 };
    int n = sizeof(arr) / sizeof(arr[0]);
  
    // function call to print required answer
    cout << countSequences(arr, n);
    return 0;
}

chevron_right


Java

filter_none

edit
close

play_arrow

link
brightness_4
code

// Java  program find the minimum number of consecutive 
// sequences in an array
  
import java.util.Arrays; 
import java.io.*;
  
class GFG {
      
static int countSequences(int arr[], int n)
{
    int count = 1;
  
    Arrays.sort(arr);
  
    for (int i = 0; i < n - 1; i++)
        if (arr[i] + 1 != arr[i + 1])
            count++;
  
    return count;
}
  
// Driver program
    public static void main (String[] args) {
  
    int arr[] = { 1, 7, 3, 5, 10 };
    int n = arr.length;
    // function call to print required answer
    System.out.println( countSequences(arr, n));
  
    }
//This code is contributed by ajit.    
}

chevron_right


Python3

filter_none

edit
close

play_arrow

link
brightness_4
code

# Python3 program find the minimum number of consecutive 
# sequences in an array 
  
def countSequences(arr, n) :
    count = 1
  
    arr.sort()
  
    for i in range( n -1) : 
        if (arr[i] + 1 != arr[i + 1]) :
            count += 1
  
    return count 
   
  
# Driver program 
if __name__ == "__main__" :
  
    arr = [ 1, 7, 3, 5, 10
    n = len(arr)
  
    # function call to print required answer 
    print(countSequences(arr, n)) 
  
# This code is contributed by Ryuga

chevron_right


C#

filter_none

edit
close

play_arrow

link
brightness_4
code

// C# program find the minimum number of consecutive 
// sequences in an array
 using System;
class GFG {
       
static int countSequences(int []arr, int n)
{
    int count = 1;
   
    Array.Sort(arr);
   
    for (int i = 0; i < n - 1; i++)
        if (arr[i] + 1 != arr[i + 1])
            count++;
   
    return count;
}
   
// Driver program
    static public void Main (String []args) {
   
    int []arr = { 1, 7, 3, 5, 10 };
    int n = arr.Length;
    // function call to print required answer
    Console.WriteLine( countSequences(arr, n));
   
    }
}
//This code is contributed by Arnab Kundu   

chevron_right


PHP

Output:

5

Time Complexity : O(n log n), where n is the size of the array.



My Personal Notes arrow_drop_up

Check out this Author's contributed articles.

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.