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Two integers are called "friend numbers" if they share the same sum of their digits, and the sum is their "friend ID". For example, 123 and 51 are fri 阅读全文
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John got a full mark on PAT. He was so happy that he decided to hold a raffle（抽奖） for his followers on Weibo -- that is, he would select winners from 阅读全文
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Consider a positive integer N written in standard notation with k+1 digits ai as ak⋯a1a0 with 0≤ai<10 for all i and ak>0. Then N is 阅读全文
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Given N integers, you are supposed to find the smallest positive integer that is NOT in the given list. Input Specification: Each input file contains 阅读全文
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A reversible prime in any number system is a prime whose "reverse" in that number system is also a prime. For example in the decimal system 73 is a re 阅读全文
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With the 2010 FIFA World Cup running, football fans the world over were becoming increasingly excited as the best players from the best teams doing ba 阅读全文
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The highest building in our city has only one elevator. A request list is made up with N positive numbers. The numbers denote at which floors the elev 阅读全文
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At the beginning of every day, the first person who signs in the computer room will unlock the door, and the last one who signs out will lock the door 阅读全文
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Given a non-negative integer N, your task is to compute the sum of all the digits of N, and output every digit of the sum in English. Input Specificat 阅读全文
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Calculate a+b and output the sum in standard format -- that is, the digits must be separated into groups of three by commas (unless there are less tha 阅读全文