Given an integer N, the task is to check if it is a Centered triangular number or not.
Centered triangular number is a centered polygonal number that represents a triangle with a dot in the centre and all other dots surrounding the centre in successive triangular layers . The first few Centered triangular numbers are 1, 4, 10, 19, 31, 46, 64, 85, 109, 136, …
Examples:
Input: N = 4
Output: Yes
Input: 20
Output: No
Approach:
- The Kth Centered triangular number can be expressed as:
- In order to check if the given number N can be expressed as a Centered triangular number or not, we need to check if
gives an integer or not.
Below is the implementation of the above approach:
// C++ implementation to check // whether a given number is a // Centered triangular number or not #include <bits/stdc++.h> using namespace std;
// Function to check if the // number is a Centered // Triangular Number bool isCenteredtriangular( int N)
{ float K = (-3
+ sqrt (24 * N - 15))
/ 6;
// Condition for K to be
// an integer
return (K - ( int )K) == 0;
} // Driver Code int main()
{ int N = 85;
if (isCenteredtriangular(N)) {
cout << "Yes" ;
}
else {
cout << "No" ;
}
return 0;
} |
// Java implementation to check that // a number is a centered triangular // number or not import java.lang.Math;
class GFG{
// Function to check that the number // is a centered triangular number public static boolean isCenteredTriangular( int N)
{ double K = (- 3 + Math.sqrt( 24 * N - 15 )) / 6 ;
// Condition to check if the number
// is a centered triangular number
return (K - ( int )K) == 0 ;
} // Driver Code public static void main(String[] args)
{ int N = 85 ;
// Function call
if (isCenteredTriangular(N))
{
System.out.println( "Yes" );
}
else
{
System.out.println( "No" );
}
} } // This code is contributed by ShubhamCoder |
# Python3 implementation to check # whether a given number is a # Centered triangular number or not import math
# Function to check if the # number is a Centered # Triangular Number def isCenteredtriangular(N):
K = ( - 3 + math.sqrt( 24 * N - 15 )) / 6
# Condition for K to be
# an integer
if (K - int (K)) = = 0 :
return True
return False
# Driver Code # Given Number N = 85
# Function call if (isCenteredtriangular(N)):
print ( "Yes" )
else :
print ( "No" )
# This code is contributed by shubhamsingh10 |
// C# implementation to check whether // a given number is a centered // triangular number or not using System;
class GFG{
// Function to check if the number // is a centered triangular number static bool isCenteredtriangular( int N)
{ double K = (-3 + Math.Sqrt(24 * N - 15)) / 6;
// Condition for K to be
// an integer
return (K - ( int )K) == 0;
} // Driver Code static public void Main ()
{ int N = 85;
if (isCenteredtriangular(N))
{
Console.Write( "Yes" );
}
else
{
Console.Write( "No" );
}
} } // This code is contributed by shubhamsingh10 |
<script> // JavaScript implementation to check // whether a given number is a // Centered triangular number or not // Function to check if the // number is a Centered // Triangular Number function isCenteredtriangular(N)
{ var K = (-3
+ Math.sqrt(24 * N - 15))
/ 6;
// Condition for K to be
// an integer
return (K - parseInt(K)) == 0;
} // Driver Code var N = 85;
if (isCenteredtriangular(N)) {
document.write( "Yes" );
} else {
document.write( "No" );
} </script> |
Output:
Yes
Time Complexity: O(logN) because inbuilt sqrt function is being used
Auxiliary Space: O(1)