-
Notifications
You must be signed in to change notification settings - Fork 0
New issue
Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.
By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.
Already on GitHub? Sign in to your account
Kropotov - algo - hw04 #2
base: main
Are you sure you want to change the base?
Changes from all commits
File filter
Filter by extension
Conversations
Jump to
Diff view
Diff view
There are no files selected for viewing
Original file line number | Diff line number | Diff line change |
---|---|---|
@@ -0,0 +1,26 @@ | ||
from random import randint | ||
import timeit | ||
|
||
|
||
def f2(a): | ||
min_e = float('inf') | ||
max_e = float('-inf') | ||
for e in a: | ||
min_e = e if e < min_e else min_e | ||
max_e = e if e > max_e else max_e | ||
for idx, e in enumerate(a): | ||
a[idx] = max_e if e == min_e else (min_e if e == max_e else e) | ||
return a | ||
|
||
|
||
a100 = [randint(-100, 100) for n1 in range(100)] | ||
a200 = [randint(-200, 200) for n2 in range(200)] | ||
a300 = [randint(-300, 300) for n3 in range(300)] | ||
|
||
|
||
print(timeit.timeit('f2(a100)', globals=globals())) # 19.445062 | ||
print(timeit.timeit('f2(a200)', globals=globals())) # 41.943428600000004 | ||
print(timeit.timeit('f2(a300)', globals=globals())) # 63.8597697 | ||
|
||
# можно сделать вывод что сложность алгоритма O(n), т.е. пропорциональна размеру входного массива | ||
|
Original file line number | Diff line number | Diff line change |
---|---|---|
@@ -0,0 +1,77 @@ | ||
import math | ||
import timeit | ||
|
||
|
||
def find_prime(pos): | ||
ind = 1 | ||
simples = [2] | ||
cur = 3 | ||
while ind < pos: | ||
rest = 0 | ||
for d in simples: | ||
rest = cur % d | ||
if rest == 0: | ||
break | ||
if rest != 0: | ||
simples.append(cur) | ||
ind += 1 | ||
cur += 2 | ||
return simples[len(simples) - 1] | ||
There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more.
|
||
|
||
|
||
print(find_prime(10)) | ||
print(timeit.timeit('find_prime(10)', globals=globals(), number=100000)) | ||
|
||
print(find_prime(20)) | ||
print(timeit.timeit('find_prime(20)', globals=globals(), number=100000)) | ||
|
||
print(find_prime(40)) | ||
print(timeit.timeit('find_prime(40)', globals=globals(), number=100000)) | ||
|
||
|
||
def find_prime_re(pos): | ||
lim = math.ceil(2 * pos * math.log(pos)) | ||
ma = list(range(2, lim)) | ||
start_ind = 0 | ||
cur_simple = 0 | ||
res = 0 | ||
while start_ind < len(ma): | ||
There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more.
|
||
if ma[start_ind] != 0: | ||
cur_simple += 1 | ||
if cur_simple == pos: | ||
res = ma[start_ind] | ||
break | ||
step = ma[start_ind] | ||
cur_pos = start_ind + step | ||
while cur_pos < len(ma): | ||
ma[cur_pos] = 0 | ||
cur_pos += step | ||
start_ind += 1 | ||
return res | ||
|
||
|
||
print(find_prime_re(10)) | ||
print(timeit.timeit('find_prime_re(10)', globals=globals(), number=100000)) | ||
print(find_prime_re(20)) | ||
print(timeit.timeit('find_prime_re(20)', globals=globals(), number=100000)) | ||
print(find_prime_re(40)) | ||
print(timeit.timeit('find_prime_re(40)', globals=globals(), number=100000)) | ||
|
||
# 29 | ||
# 0.6340101 | ||
# 71 | ||
# 1.9487579999999998 | ||
# 173 | ||
# 6.395146 | ||
# 29 | ||
# 1.2755858 | ||
# 71 | ||
# 3.2944619 | ||
# 173 | ||
# 11.313060799999999 | ||
|
||
# Видимо не правильно реализовал второй алгоритм, хотя делал как понял. | ||
# Нужно было определить верхню границу для i-го простого числа, нашел формулу 2*n*ln(n) | ||
Comment on lines
+73
to
+74
There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more. реализация правильная (в алгоритмическом смысле). Просто не самый эффективный код написан, ничего страшного в этом нету :) |
||
|
||
|
||
|
There was a problem hiding this comment.
Choose a reason for hiding this comment
The reason will be displayed to describe this comment to others. Learn more.
тут все же лучше проверять через отдельные условия. Иначе много раз будем перезаписывать одни и те же значения в массив, что не очень хорошо