All Questions
11
questions
2
votes
2
answers
172
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Project Euler, Problem 273: finding perfect-square partitions
Problem:
Consider equations of the form: \$a^2 + b^2 = N; 0 \leq a \leq b; a, b, N \in \mathbb{N}\$.
For \$N=65\$ there are two solutions:
\$a=1, b=8\$ and \$a=4, b=7\$.
We call \$S(...
- 41
8
votes
3
answers
1k
views
Balanced centrifuge configurations
Given an input N as the size of a centrifuge, I need to find out the number of balanced configurations. The full description is here.
Centrifuge is a piece of ...
- 317
8
votes
1
answer
330
views
Find "prime polynomials" for a user's given prime, bounds, and degree
Very amateur programmer and first-time poster here.
The program I wrote asks the user for a prime number, a lower and upper bound, and a degree (all of these are integers). I want to generate a list ...
- 183
5
votes
2
answers
3k
views
Project Euler Problem 21 in Python: Summing amicable numbers
Let d(n) be defined as the sum of proper divisors of n (numbers less than n which divide evenly into n).
If d(a) = b and d(b) = a, where a ≠ b, then a and b are an amicable pair and each of a and b ...
- 87
5
votes
3
answers
2k
views
Find smallest number of squares that sum to a number
Leetcode problem 279 “Perfect Squares” is:
Given a positive integer n, find the least number of perfect square numbers (for example, 1, 4, 9, 16, ...)
I wrote the following solution:
...
- 459
9
votes
3
answers
7k
views
Odd divisor summation
Given an integer, k, we define its odd divisor sum to be the sum of all k's odd divisors. For example, if k = 20, then the odd divisor sum would be 1 + 5 = 6. Similarly, if given an array of values, ...
3
votes
2
answers
588
views
Time limit exceeded on finding out the GCD and LCM of a Python list
I'm doing this HackerRank problem:
Consider two sets of positive integers, \$A=\{a_0, a_1, \ldots, a_{n-1}\}\$ and \$B=\{b_0, b_1, \ldots, b_{m-1}\}\$. We say that a positive integer, \$x\$, is ...
- 493
4
votes
3
answers
303
views
Time Limit Exceeded for ETF - Euler Totient Function at Spoj
In number theory, the totient φ of a positive integer n is defined to be the number of positive integers less than or equal to n that are coprime to n.
Given an integer n (1 ≤ n ≤ 106), compute the ...
- 241
5
votes
6
answers
9k
views
Counting pairs of relatively prime numbers
Problem from Hacker Earth:
Inverted GCD:
Given an array a of \$N\$ numbers , you have to find the number of pair of indices \$i\$ and \$j\$ that satisfy the following relation:
\$i <...
- 455
3
votes
1
answer
2k
views
Project Euler #549: Divisibility of factorials
This is the problem:
Calculate
$$\sum_{i=2}^{10^8} s(i)$$
where \$s(n)\$ is the smallest \$m\$ such that \$n\$ divides \$m!\$.
Quite mathematical, I've found a better way than brute ...
- 131
6
votes
2
answers
409
views
Central Delannoy numbers
I am solving this problem on SPOJ Upper Right King (Hard):
There is a king in the lower left corner of the \$ n \times n \$ chess board. The king can move one step right, one step up or one step up-...
- 61