欧拉编程

raa

http://projecteuler.net/index.php 上有很多题，等着大家编程练手。 应该不会很难的？

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nice job About Register Problems Login Problems Problem 262 will be accessible in 1 day, 9 hours, 19 minutes (Fri 30 Oct 2009 at 9.00 pm [GMT]) Current date/time on server: Thu 29 Oct 2009 11.41 am [GMT] Page: 123456 ID Description / Title Solved By 1 Add all the natural numbers below one thousand that are multiples of 3 or 5. 76780 2 Find the sum of all the even-valued terms in the Fibonacci sequence which do not exceed four million. 64264 3 Find the largest prime factor of a composite number. 47019 4 Find the largest palindrome made from the product of two 3-digit numbers. 43904 5 What is the smallest number divisible by each of the numbers 1 to 20? 50238 6 What is the difference between the sum of the squares and the square of the sums? 51431 7 Find the 10001st prime. 42838 8 Discover the largest product of five consecutive digits in the 1000-digit number. 38556 9 Find the only Pythagorean triplet, {a, b, c}, for which a + b + c = 1000. 38302 10 Calculate the sum of all the primes below two million. 34612 11 What is the greatest product of four numbers on the same straight line in the 20 by 20 grid? 26717 12 What is the value of the first triangle number to have over five hundred divisors? 22862 13 Find the first ten digits of the sum of one-hundred 50-digit numbers. 27166 14 Find the longest sequence using a starting number under one million. 25679 15 Starting in the top left corner in a 20 by 20 grid, how many routes are there to the bottom right corner? 21054 16 What is the sum of the digits of the number 21000? 28406 17 How many letters would be needed to write all the numbers in words from 1 to 1000? 17844 18 Find the maximum sum travelling from the top of the triangle to the base. 18181 19 How many Sundays fell on the first of the month during the twentieth century? 16723 20 Find the sum of digits in 100! 27379 21 Evaluate the sum of all amicable pairs under 10000. 18052 22 What is the total of all the name scores in the file of first names? 17144 23 Find the sum of all the positive integers which cannot be written as the sum of two abundant numbers. 11879 24 What is the millionth lexicographic permutation of the digits 0, 1, 2, 3, 4, 5, 6, 7, 8 and 9? 14789 25 What is the first term in the Fibonacci sequence to contain 1000 digits? 21276 26 Find the value of d < 1000 for which 1/d contains the longest recurring cycle. 10289 27 Find a quadratic formula that produces the maximum number of primes for consecutive values of n. 10750 28 What is the sum of both diagonals in a 1001 by 1001 spiral? 16330 29 How many distinct terms are in the sequence generated by ab for 2 ≤ a ≤ 100 and 2 ≤ b ≤ 100? 13445 30 Find the sum of all the numbers that can be written as the sum of fifth powers of their digits. 15024 31 Investigating combinations of English currency denominations. 10181 32 Find the sum of all numbers that can be written as pandigital products. 8636 33 Discover all the fractions with an unorthodox cancelling method. 9645 34 Find the sum of all numbers which are equal to the sum of the factorial of their digits. 13190 35 How many circular primes are there below one million? 11970 36 Find the sum of all numbers less than one million, which are palindromic in base 10 and base 2. 13471 37 Find the sum of all eleven primes that are both truncatable from left to right and right to left. 9774 38 What is the largest 1 to 9 pandigital that can be formed by multiplying a fixed number by 1, 2, 3, ... ? 8067 39 If p is the perimeter of a right angle triangle, {a, b, c}, which value, for p ≤ 1000, has the most solutions? 9726 40 Finding the nth digit of the fractional part of the irrational number. 11562 41 What is the largest n-digit pandigital prime that exists? 8973 42 How many triangle words does the list of common English words contain? 11075 43 Find the sum of all pandigital numbers with an unusual sub-string divisibility property. 7287 44 Find the smallest pair of pentagonal numbers whose sum and difference is pentagonal. 6932 45 After 40755, what is the next triangle number that is also pentagonal and hexagonal? 10382 46 What is the smallest odd composite that cannot be written as the sum of a prime and twice a square? 7298 47 Find the first four consecutive integers to have four distinct primes factors. 7428 48 Find the last ten digits of 11 + 22 + ... + 10001000. 18629 49 Find arithmetic sequences, made of prime terms, whose four digits are permutations of each other. 7102 50 Which prime, below one-million, can be written as the sum of the most consecutive primes? 7643 Page: 123456 Project Euler Copyright Information

jmouse

那里不光靠编程，还是需要动动脑子找点方法的，否则那些大数够你跑的，或者要找个好点的工具。 曾经迷恋Ruby的时候上去做了87道题，现在总数都快262了。

风云剑

呵呵，难度不小的。