Project Euler

[001] Multiples of 3 and 5

import time
t = time.time()

result = 0
for i in range(1, 100):
	if(i % 3 == 0 or i % 5 == 0):
		result += i
		
print("RESULT : " + str(result))
print("\n[RUNTIME ::  %.02f]" % (time.time() - t))

[002] Even Fibonacci numbers # 피보나치수열 홀짝되는 규칙찾으면 더빨라져

import time
t = time.time()

result = 2 # Because curNum starts in 3, result is initiated by 2
first, second = 1, 2
curNum = 0
while curNum <= 4000000:
	curNum = first + second
	if(curNum % 2 == 0): result += curNum
	first, second = second, curNum
	
print("RESULT : " +str(result))
print("\n[RUNTIME ::  %.02f]" % (time.time() - t))

[003] Largest prime factor

import time
t = time.time()

NUMBER = 600851475143
curPrime = 2

#Return Next Prime Number
def nextPrime(curPrime):
	curPrime += 1
	while 1:
		for n in range(2, curPrime):
			if(curPrime % n == 0):
				curPrime += 1
				break
			elif(n == curPrime-1):
				return curPrime
#main
while 1:
	if(NUMBER % curPrime == 0): NUMBER /= curPrime
	elif(NUMBER == 1): break
	else: curPrime = nextPrime(curPrime)

print("The Largest Prime Factor : %d" % curPrime)
print("\n[RUNTIME ::  %.02f]" % (time.time() - t))

[004] Largest palindrome product # 대칭수가 11의배수라는데?

import time
t = time.time()

cur = 0
result = 0
for a in range(100, 1000):
	for b in range(100, 1000):
		cur = a * b
		if(cur < 100000):
			if(int(cur/10000) == cur%10 and int(cur/1000)%10 == int(cur/10)%10):
				if(result < cur): result = cur
		else:
			if(int(cur/100000) == cur%10 and int(cur/10000)%10 == int(cur/10)%10 and int(cur/1000)%10 == int(cur/100)%10):
				if(result < cur): result = cur

print("RESULT : %d" % result)
print("\n[RUNTIME ::  %.03f]" % (time.time() - t))

[005] Smallest multiple

import time
t = time.time()

def nextPrime(curPrime):
	curPrime += 1
	while 1:
		for n in range(2, curPrime):
			if(curPrime % n == 0):
				curPrime += 1
				break
			elif(n == curPrime-1):
				return curPrime

ans, prime = 1, 2
list = []
for i in range(1, 21): list.append(i)
while(1):
	notChange = 1
	oneCount = 0
	for i in range(0, 20):
		if(list[i] % prime == 0):
			list[i] = int(list[i] / prime)
			notChange = 0
		elif(list[i] == 1): oneCount += 1
	if(oneCount == 20):
		break
	elif(notChange): prime = nextPrime(prime)
	else: ans *= prime

print("ANS : %d" % ans)
print("\n[RUNTIME ::  %f]" % (time.time() - t))

[006] Sum square difference # 시그마 공식 걍썼는데??

import time
t = time.time()

k = 100
sumOfSquares = int((k)*(k+1)*(2*k+1)/6)
squareOfSum = (int(k*(k+1)/2)) ** 2
ans = abs(sumOfSquares - squareOfSum)
print("ANS : %d" % ans)

print("\n[RUNTIME ::  %.02f]" % (time.time() - t))

[007] 10001st prime # 내가 좀 멍청해서 브르투포스 # 224초였던가??

import time
t = time.time()

count = 1
curPrime = 2
while 1:
	n = 2
	while 1:
		if(curPrime % n == 0):
			curPrime += 1
			break
		elif(n == curPrime-1):
			count += 1
			print("%d %% %d [%d]" % (curPrime, n, count))
			curPrime += 1
			break
		n += 1
	if(count == 10001):
		curPrime -= 1
		break
		
print("ANS : %d" % curPrime)
print("\n[RUNTIME ::  %.02f]" % (time.time() - t))