Soluție HackerRank pentru Shashank and List, subdomeniul Algebra, în Python 3. Include cerința formatată, exemple, explicația pașilor și cod sursă.
- Problemă: Shashank and List
- Domeniu: Algebra
- Limbaj: Python 3
Challenge: Shashank and List
Subdomeniu: Algebra (algebra)
Scor cont: 20.0 / 20
Submission status: Accepted
Submission score: 1.0
Submission ID: 464740228
Limbaj: python3
Link challenge: https://www.hackerrank.com/challenges/shashank-and-list/problem
Cerință
Shashank is a newbie to mathematics, and he is very excited after knowing that a given l of cardinality N has (_2<sup>N</sup> - 1_) non-empty sublist. He writes down all the non-empty sublists for a given set A. For each sublist, he calculates sublist_sum, which is the sum of elements and denotes them by S<sub>1</sub>, S<sub>2</sub>, S<sub>3</sub>, ... , S<sub>(2<sup>N</sup>-1)</sub>.
He then defines a special_sum, P.
P = 2<sup>S<sub>1</sub> </sup> + 2<sup>S<sub>2</sub> </sup> + 2<sup>S<sub>3</sub> </sup> .... + 2<sup>S<sub>(2<sup>N</sup>-1)</sub> </sup>and reports P % (10<sup>9</sup> + 7).
Input Format
The first line contains an integer N, i.e., the size of list A.
The next line will contain N integers, each representing an element of list A.
Output Format
Print special_sum, P _modulo (10<sup>9</sup> + 7)_.
Constraints
1 ≤ N ≤ 10<sup>5</sup>
0 ≤ _a<sub>i</sub>_ ≤ 10<sup>10</sup> , where _i ∈ [1 .. N]_
Sample Input
3
1 1 2
Sample Output
44
Explanation
For given list, sublist and calculations are given below
1. {1} and 2<sup>1</sup> = 2
2. {1} and 2<sup>1</sup> = 2
3. {2} and 2<sup>2</sup> = 4
4. {1,1} and 2<sup>2</sup> = 4
5. {1,2} and 2<sup>3</sup> = 8
6. {1,2} and 2<sup>3</sup> = 8
7. {1,1,2} and 2<sup>4</sup> = 16
So total sum will be 44.
Cod sursă
import sys
MOD = 1000000007
def main():
data = sys.stdin.buffer.read().split()
if not data:
return
n = int(data[0])
arr = list(map(int, data[1:1 + n]))
ans = 1
for x in arr:
ans = (ans * (1 + pow(2, x, MOD))) % MOD
ans = (ans - 1) % MOD
print(ans)
if __name__ == '__main__':
main()