摘要：Roman numeralsFor a number written in Roman numerals to be considered valid there are basic rules which must be followed. Even though the rules allow ... 阅读全文

摘要：Product-sum numbersA natural number, N, that can be written as the sum and product of a given set of at least two natural numbers, {a1, a2, … , ak} is... 阅读全文

摘要：Prime power triplesThe smallest number expressible as the sum of a prime square, prime cube, and prime fourth power is 28. In fact, there are exactly ... 阅读全文

摘要：Cuboid routeA spider, S, sits in one corner of a cuboid room, measuring 6 by 5 by 3, and a fly, F, sits in the opposite corner. By travelling on the s... 阅读全文

摘要：Counting rectanglesBy counting carefully it can be seen that a rectangular grid measuring 3 by 2 contains eighteen rectangles:Although there exists no... 阅读全文

摘要：Monopoly oddsIn the game,Monopoly, the standard board is set up in the following way:GOA1CC1A2T1R1B1CH1B2B3JAILH2C1T2U1H1C2CH3C3R4R2G3D1CC3CC2G2D2G1D3... 阅读全文

摘要：Path sum: four waysNOTE: This problem is a significantly more challenging version ofProblem 81.In the 5 by 5 matrix below, the minimal path sum from t... 阅读全文

摘要：Path sum: three waysNOTE: This problem is a more challenging version ofProblem 81.The minimal path sum in the 5 by 5 matrix below, by starting in any ... 阅读全文

摘要：Path sum: two waysIn the 5 by 5 matrix below, the minimal path sum from the top left to the bottom right, byonly moving to the right and down, is indi... 阅读全文

摘要：Square root digital expansionIt is well known that if the square root of a natural number is not an integer, then it is irrational. The decimal expans... 阅读全文

摘要：Passcode derivationA common security method used for online banking is to ask the user for three random characters from a passcode. For example, if th... 阅读全文

摘要：Coin partitions Let p(n) represent the number of different ways in which n coins can be separated into piles. For example, five coins can separated into piles in exactly seven different ways, so p(5)=... 阅读全文

摘要：原题：Prime summationsIt is possible to write ten as the sum of primes in exactly five different ways:7 + 35 + 55 + 3 + 23 + 3 + 2 + 22 + 2 + 2 + 2 + 2Wh... 阅读全文

摘要：题目链接原题：It is possible to write five as a sum in exactly six different ways:4 + 13 + 23 + 1 + 12 + 2 + 12 + 1 + 1 + 11 + 1 + 1 + 1 + 1How many differen... 阅读全文

摘要：题目链接原题：It turns out that 12 cm is the smallest length of wire that can be bent to form an integer sided right angle triangle in exactly one way, but t... 阅读全文

摘要：Euler Level3 规范化程序： 包名：LevelX，X是等级 每题程序名：PE0xx.java，PE0xx.py 程序有必要的注释，不同方法运行结果也在程序中 规范化博文： 名字：ProjectEuler：xxxxx 题目链接 英语题目 翻译题目 解题思路 java程序 python程序 运 阅读全文

摘要：题目链接：https://projecteuler.net/problem=74数字145有一个著名的性质：其所有位上数字的阶乘和等于它本身。1! + 4! + 5! = 1 + 24 + 120 = 145169不像145那么有名，但是169可以产生最长的能够连接回它自己的数字链。事实证明一共有三... 阅读全文

摘要：题目链接：https://projecteuler.net/problem=73n/d的真分数 ，当d《=12000时 在1/3 and 1/2 之间的有多少个public class P73{ void run(){ FareySequences(); }... 阅读全文

摘要：题目链接：https://projecteuler.net/problem=72真分数;n/d当d≤ 1,000,000时候的真分数有多少个public class P72{ void run(){ int max_n = 1000000; long[] phi =... 阅读全文

摘要：题目链接：https://projecteuler.net/problem=71Ifn2;q--){ p = (a*q-1)/b; if(p*s>r*q){ s = q; r = p; ... 阅读全文