Python中的Euler#8项目 “” 在1000位数字中找出五个连续数字的最大乘积 ''' 导入时间 num='1\ 73167176531330624919225119674426574742355349194934\ 96983520312774506326239578318016984801869478851843\ 85861560789112949495459501737958331952853208805511\ 12540698747158523863050715693290963295227443043557\ 66896648950445244523161731856403098711121722383113\ 62229893423380308135336276614282806444486645238749\ 30358907296290491560440772390713810515859307960866\ 70172427121883998797908792274921901699720888093776\ 65727333001053367881220235421809751254540594752243\ 52584907711670556013604839586446706324415722155397\ 53697817977846174064955149290862569321978468622482\ 83972241375657056057490261407972968652414535100474\ 82166370484403199890008895243450658541227588666881\ 16427171479924442928230863465674813919123162824586\ 17866458359124566529476545682848912883142607690042\ 24219022671055626321111109370544217506941658960408\ 07198403850962455444362981230987879927244284909188\ 84580156166097919133875499200524063689912560717606\ 05886116467109405077541002256983155200055935729725\ 71636269561882670428252483600823257530420752963450' 最大值=0 i=1 而i最大： 最大=产品 i+=i+1 印刷品（产品） 开始=时间。时间（） 已用=（time.time（）-start） 打印（“此代码耗时：“+str（已用时间）+”秒”）

这个代码给我的答案是7054，太低了，应该会计算很多产品，但只计算其中的9个。我的问题是：是什么导致我的代码偏离其预期目的，以及如何优化代码中计算“1”、“2”等的部分以计算产品？谢谢你的建议

问题在于：

'''
Find the greatest product of five consecutive digits in the 1000-digit number
'''

import time

num = '\
73167176531330624919225119674426574742355349194934\
96983520312774506326239578318016984801869478851843\
85861560789112949495459501737958331952853208805511\
12540698747158523863050715693290963295227443043557\
66896648950445244523161731856403098711121722383113\
62229893423380308135336276614282806444486645238749\
30358907296290491560440772390713810515859307960866\
70172427121883998797908792274921901699720888093776\
65727333001053367881220235421809751254540594752243\
52584907711670556013604839586446706324415722155397\
53697817977846174064955149290862569321978468622482\
83972241375657056057490261407972968652414535100474\
82166370484403199890008895243450658541227588666881\
16427171479924442928230863465674813919123162824586\
17866458359124566529476545682848912883142607690042\
24219022671055626321111109370544217506941658960408\
07198403850962455444362981230987879927244284909188\
84580156166097919133875499200524063689912560717606\
05886116467109405077541002256983155200055935729725\
71636269561882670428252483600823257530420752963450'

biggest = 0
i = 1
while i < len(num):
    one = int(num[i]) 
    two = int(num[i+1])  
    thr = int(num[i+2]) 
    fou = int(num[i+3])
    fiv = int(num[i+4])
    product = one*two*thr*fou*fiv
    if product > biggest:
        biggest = product
    i += i+1 
 print(product)

 start = time.time()
 elapsed = (time.time() - start)
 print("This code took: " + str(elapsed) + " seconds")

您每次都要加倍

i

，并向其添加

1

。因此，如果

i

为1，则将其设为3。如果是3，就等于7。如果是7，就等于15，依此类推。但这意味着你的索引缺少很多地方，不是吗

这会导致您跳过数字中的许多位置。您要使用：

i += i+1

这只意味着将1添加到

i

或者你可以：

i += 1

这意味着，将

i

设置为等于

i+1

您的问题在于：

i = i+1

你浏览列表的速度太快了。您应该这样做：

i += i+1

我会这样写代码：

i += 1

计算乘积的更简单方法如下：

import operator

# Return the product of all the digits in `series` converted to integers
def numprod(series):
    # Convert the series of digits into a list of integers
    digits = [int(c) for c in series]

    # This applies the multiplication operator to all the digits,
    # starting with 1
    return reduce(operator.__mul__, digits, 1)

# Produce every string of length 5
# This uses a generator but could just as easily use a list comprehension:
# numiter = [num[i : i + SERIES_SIZE] for i in range(len(num) - SERIES_SIZE + 1)]
SERIES_SIZE = 5
numiter = (num[i : i + SERIES_SIZE] for i in range(len(num) - SERIES_SIZE + 1))

# Calculate all the products
allnumprods = [numprod(series) for series in numiter]

# Find the maximum of all the products
print max(allnumprods)

---

有几个问题

您正在打印

产品

而不是

最大的

。确保打印正确的变量

在遍历整个字符串的长度时，实际上应该在

[0..len（num）-4）

范围内进行迭代，这样在进行乘积计算时就不会得到索引器

您将i变量的值递增错误。您希望每回合递增1，所以只需执行

i+=1

或

i=i+1

。代码

i+=i+1

相当于

i=i+1

。我不认为您希望在while循环的每次迭代中都加倍

i

。）

在Python中，序列是0索引的。这意味着当您迭代一组索引时，第一个元素始终位于

seq[0]

，并且这些元素一直持续到

seq[n-1]

。因此，您应该将

i

变量从0开始，而不是从1开始

您没有正确地测量时间。您希望在所有代码执行之前分配

开始时间

时间，以便正确测量

已用时间

时间

这是您的固定代码：

def numprod(series):
    product = 1
    for c in series:
        product *= int(c)
    return product

“”
在1000位数字中找出五个连续数字的最大乘积
'''
导入时间
开始=时间。时间（）
num='1\
73167176531330624919225119674426574742355349194934\
96983520312774506326239578318016984801869478851843\
85861560789112949495459501737958331952853208805511\
12540698747158523863050715693290963295227443043557\
66896648950445244523161731856403098711121722383113\
62229893423380308135336276614282806444486645238749\
30358907296290491560440772390713810515859307960866\
70172427121883998797908792274921901699720888093776\
65727333001053367881220235421809751254540594752243\
52584907711670556013604839586446706324415722155397\
53697817977846174064955149290862569321978468622482\
83972241375657056057490261407972968652414535100474\
82166370484403199890008895243450658541227588666881\
16427171479924442928230863465674813919123162824586\
17866458359124566529476545682848912883142607690042\
24219022671055626321111109370544217506941658960408\
07198403850962455444362981230987879927244284909188\
84580156166097919133875499200524063689912560717606\
05886116467109405077541002256983155200055935729725\
71636269561882670428252483600823257530420752963450'
最大值=0
i=0
而i最大：
最大=产品
i=i+1
打印（最大）
已用=（time.time（）-start）
打印（“此代码耗时：“+str（已用时间）+”秒”）

也可以使用函数式编程大大简化问题：

import string
numbers=list()
fo=open("C:/python34/libs/maths2.txt","r+")
for eachline in fo:
    for char in eachline:
        if char.isdigit():
            A=char
            numbers.append(int(A))

print(numbers)
list1=list()
for i in range(0,len(numbers)-4):
    x=numbers[i]*numbers[i+1]*numbers[i+2]*numbers[i+3]*numbers[i+4]
    list1.append([x])
print(list1)
print(max(list1))

---

再试一次！

这不是优化的，但它适用于13位数字

def foo():
    max_product = 0
    num = "string of input number"
    for e,n in enumerate(num):
        product = reduce((lambda x,y: x*y),map(int,(num[e:e+13])))
        if product > max_product: 
            max_product = product
    return max_product

导入时间
开始时间=time.time（）
num=“73167176531330624919225119744265742355349194934\
96983520312774506326239578318016984801869478851843\
85861560789112949495459501737958331952853208805511\
12540698747158523863050715693290963295227443043557\
66896648950445244523161731856403098711121722383113\
62229893423380308135336276614282806444486645238749\
30358907296290491560440772390713810515859307960866\
70172427
def foo():
    max_product = 0
    num = "string of input number"
    for e,n in enumerate(num):
        product = reduce((lambda x,y: x*y),map(int,(num[e:e+13])))
        if product > max_product: 
            max_product = product
    return max_product

import time
start_time = time.time()
num = "73167176531330624919225119674426574742355349194934\
96983520312774506326239578318016984801869478851843\
85861560789112949495459501737958331952853208805511\
12540698747158523863050715693290963295227443043557\
66896648950445244523161731856403098711121722383113\
62229893423380308135336276614282806444486645238749\
30358907296290491560440772390713810515859307960866\
70172427121883998797908792274921901699720888093776\
65727333001053367881220235421809751254540594752243\
52584907711670556013604839586446706324415722155397\
53697817977846174064955149290862569321978468622482\
83972241375657056057490261407972968652414535100474\
82166370484403199890008895243450658541227588666881\
16427171479924442928230863465674813919123162824586\
17866458359124566529476545682848912883142607690042\
24219022671055626321111109370544217506941658960408\
07198403850962455444362981230987879927244284909188\
84580156166097919133875499200524063689912560717606\
05886116467109405077541002256983155200055935729725\
71636269561882670428252483600823257530420752963450"
i = 0
j = 0
k = 0
while i < len(num) - 13:
    one = int(num[i])
    two = int(num[i + 1])
    three = int(num[i + 2])
    four = int(num[i + 3])
    five = int(num[i + 4])
    six = int(num[i + 5])
    seven = int(num[i + 6])
    eight = int(num[i + 7])
    nine = int(num[i + 8])
    ten = int(num[i + 9])
    eleven = int(num[i + 10])
    twoelve = int(num[i + 11])
    thirteen = int(num[i + 12])
    j = one * two * three * four * five * six * seven * eight * nine * ten * eleven * twoelve * thirteen
    i = i + 1
    if k < j:
        k = j
print(k)
print(time.time() - start_time," seconds")

# 8 Largest product in a series

from functools import reduce

the_num = "7316717653133062491922511967442657474235534919493496983520312774506326239578318016984801869478851843858615607891129494954595017379583319528532088055111254069874715852386305071569329096329522744304355766896648950445244523161731856403098711121722383113622298934233803081353362766142828064444866452387493035890729629049156044077239071381051585930796086670172427121883998797908792274921901699720888093776657273330010533678812202354218097512545405947522435258490771167055601360483958644670632441572215539753697817977846174064955149290862569321978468622482839722413756570560574902614079729686524145351004748216637048440319989000889524345065854122758866688116427171479924442928230863465674813919123162824586178664583591245665294765456828489128831426076900422421902267105562632111110937054421750694165896040807198403850962455444362981230987879927244284909188845801561660979191338754992005240636899125607176060588611646710940507754100225698315520005593572972571636269561882670428252483600823257530420752963450"

the_num_lst = []
for n in the_num:
    the_num_lst.append(int(n))

x = 0
y = reduce((lambda a, b: a * b), the_num_lst[x:x + 13])
while x < 1000 - 13:
    x += 1
    z = reduce((lambda a, b: a * b), the_num_lst[x:x + 13])
    if z > y:
        y = z
print(y)

s = '''7316717653133062491922511967442657474235534919493496983520312774506326239578318016984801869478851843858615607891129494954595017379583319528532088055111254069874715852386305071569329096329522744304355766896648950445244523161731856403098711121722383113622298934233803081353362766142828064444866452387493035890729629049156044077239071381051585930796086670172427121883998797908792274921901699720888093776657273330010533678812202354218097512545405947522435258490771167055601360483958644670632441572215539753697817977846174064955149290862569321978468622482839722413756570560574902614079729686524145351004748216637048440319989000889524345065854122758866688116427171479924442928230863465674813919123162824586178664583591245665294765456828489128831426076900422421902267105562632111110937054421750694165896040807198403850962455444362981230987879927244284909188845801561660979191338754992005240636899125607176060588611646710940507754100225698315520005593572972571636269561882670428252483600823257530420752963450'''


t = list(s)
#len(t) = 1000
#t[::-1] = t[999]

r = []
q = 0
while q <= 999:
    w = int(t[q])
    r.append(w)
    q += 1

a = 0
b = 1
c = 2
d = 3
e = 4
f = 5
g = 6
h = 7
i = 8
j = 9
k = 10
l = 11
m = 12

y = []

while m<=999:
    n = r[a]*r[b]*r[c]*r[d]*r[e]*r[f]*r[g]*r[h]*r[i]*r[j]*r[k]*r[l]*r[m]
    y.append(n)
    a += 1
    b += 1
    c += 1
    d+= 1
    e+= 1
    f+= 1
    g+= 1
    h+= 1
    i+= 1
    j+= 1
    l+= 1
    k+= 1
    m+= 1
    if m >= 1000:
        break

print(y)
print(max(y))

from functools import reduce
def max_prod(x):
    return max([reduce(lambda x, y: int(x) * int(y), (x[i:i+5])) for i in range(len(x)-5)])