Challenge: Number Groups

Subdomeniu: Algebra (algebra)

Scor cont: 20.0 / 20

Submission status: Accepted

Submission score: 1.0

Submission ID: 464721395

Limbaj: python3

Link challenge: https://www.hackerrank.com/challenges/number-groups/problem

Cerinta

The positive odd numbers are sorted in ascending order as $1, 3, 5, 7, 9, 11, 13, 15, 17, 19 \ldots$, and grouped as $(1), (3, 5), (7, 9, 11), (13, 15, 17, 19), \ldots $ and so on.

Thus, the first group is $(1)$, the second group is $(3, 5)$, the third group is $(7, 9, 11)$, etc. In general, the $k^\text{th}$ group contains the next $k$ elements of the sequence. 

Given $k$, find the sum of the elements of the $k^\text{th}$ group. For example, for $k = 3$, the answer is $27$:


![image](https://s3.amazonaws.com/hr-assets/0/1511935621-d85a3653c7-Numbergroups-2.png)

Complete the function `sumOfGroup` with input integer $k$.  Return the sum of the elements of the $k$th group.

Constraints

- $1 \le k \le 10^6$  

**Subtasks**  

- For $50\%$ of the maximum score, $k \le 10^3$

Cod sursa

#!/bin/python3

import math
import os
import random
import re
import sys

def sumOfGroup(k):
    ls = k*(k+1)//2+1
    li = k*(k+1)//2-k+1
    a = [2*i-1 for i in range(li,ls)]
    return sum(a)
if __name__ == '__main__':
    fptr = open(os.environ['OUTPUT_PATH'], 'w')

    k = int(input().strip())

    answer = sumOfGroup(k)

    fptr.write(str(answer) + '\n')

    fptr.close()
HackerRank Algebra – Number Groups