Project Euler

p10.py

#!/usr/bin/env python

import sys

def sieve_of_erastothenes(till):
    primelist = [True]*(till+1)
    primelist[0] = primelist[1] = False
    nextprime = (i for i,v in enumerate(primelist) if v)

    while (True):
        try:
            prime = nextprime.next()
        except StopIteration:
            return primelist

        for i in xrange(prime*prime,till+1,prime):
            primelist[i] = False

def primelist_to_ints(primelist):
    return [i for i,v in enumerate(primelist) if v]

if __name__ == '__main__':
    till = int(sys.argv[1])
    print sum(primelist_to_ints(sieve_of_erastothenes(till)))

p11.py

#!/usr/bin/env python

# down, right, or diagonally

grid = open('grid').read().strip()

grid = [x.split(' ') for x in grid.split('\n')]

cur_set = [01,01,01,01]
cur_max = sum(cur_set)

for i in xrange(len(grid)): # y
    for j in xrange(len(grid[i])): #x
        try:
            down = [int(grid[i][j]),
                    int(grid[i+1][j]),
                    int(grid[i+2][j]),
                    int(grid[i+3][j])]
        except IndexError:
            down = [01,01,01,01] 

        try:
            right = [int(grid[i][j]),
                     int(grid[i][j+1]),
                     int(grid[i][j+2]),
                     int(grid[i][j+3])]
        except IndexError:
            right = [01,01,01,01]

        try:
            diag1 = [int(grid[i][j]),
                    int(grid[i+1][j+1]),
                    int(grid[i+2][j+2]),
                    int(grid[i+3][j+3])]
        except IndexError:
            diag = [01,01,01,01]

        try:
            diag2 = [int(grid[i][j]),
                    int(grid[i+1][j-1]),
                    int(grid[i+2][j-2]),
                    int(grid[i+3][j-3])]
        except IndexError:
            diag2 = [01,01,01,01]

        if (sum(down) > cur_max):
            cur_set = down[:]
            cur_max = sum(cur_set)
        if (sum(right) > cur_max):
            cur_set = right[:]
            cur_max = sum(cur_set)
        if (sum(diag1) > cur_max):
            cur_set = diag1[:]
            cur_max = sum(cur_set)
        if (sum(diag2) > cur_max):
            cur_set = diag2[:]
            cur_max = sum(cur_set)

print 'cur_set: %s' % cur_set
print 'cur_max: %d' % (cur_set[0]*cur_set[1]*cur_set[2]*cur_set[3])

p7.py

#!/usr/bin/env python

f = open('numbers')

maxprod = [0,0,0,0,0]
maxsum = sum(maxprod)
currprod = [0,0,0,0,0]
currsum = sum(maxprod)

for line in f:
    for i in line.strip():
        i = int(i)
        
        currsum -= currprod.pop(0)
        currprod.append(i)
        currsum += i

        if currsum > maxsum:
            maxprod = currprod[:]
            maxsum = currsum

print maxprod

prod = 1
for i in maxprod:
    prod *= i

print prod

p8.py

#!/usr/bin/env python

import math; print sum([int(i) for i in str(math.factorial(100))])

p9.py

#!/usr/bin/env python

aset = [a for a in xrange(3,501,1)]
bset = [b for b in xrange(4,501,1)]

for a in aset:
    for b in bset:
        if math.sqrt(a*a + b*b).is_integer() and a+b+math.sqrt(a*a+b*b) == 1000:
            print '%d**2 + %d**2 == %d**2; %d' % (a,b,math.sqrt(a*a+b*b),a*b*math.sqrt(a*a+b*b))
            exit(0)