Triangular Number

Triangular Number

Given a number N.Check whether it is a triangular number or not.

Note: A number is termed as a triangular number if we can represent it in the form of a triangular grid of points such that the points form an equilateral triangle and each row contains as many points as the row number, i.e., the first row has one point, the second row has two points, the third row has three points and so on.
The starting triangular numbers are 1, 3 (1+2), 6 (1+2+3), 10 (1+2+3+4).

Example 1:

Input: N=55 Output: 1 Explanation: 55 is a triangular number. It can be represented in 10 rows.

Example 2:

Input: N=56 Output: 0 Explanation: 56 is not a triangular number.

Your Task:
You need to take a number N as input parameter and returns 1 if it is a triangular number. Otherwise, it returns 0.

Constraints:
1<=N<=106

Solution:–

import java.util.*;
import java.lang.*;
import java.io.*;

public class Main
{
	public static void main (String[] args) throws java.lang.Exception
	{
		//your code here
      Scanner sc = new Scanner(System.in);
      int n = sc.nextInt();

      if(n<0)
      {
        System.out.println(0);
        return;
      }
     
      // A Triangular number must be
       // sum of first n natural numbers
      int sum=0, flag=0;
      for(int i=1;sum<=n;i++)
        {
          sum=sum+i;
          if(sum==n)
          {
            flag=1;
            break;
          } 
        }
      System.out.println(flag);
	}
}

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