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1.关系模型的三类完整性规则：实体完整性，参照完整性，用户定义的完整性规则。 1.1,数据库是指长期储存在计算机内，有组织的、可共享的大量数据的集合。数据库中的数据按照一定的数据模型组织、描述和存储， 较小的冗余度、具有较高的数据独立性和易扩展性，并可为各种用户专享。 1.2，数据库可以使用多种类型 阅读全文
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Super Jumping! Jumping! Jumping! Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 65536/32768 K (Java/Others)Total Submission(s): 32564 Accepted S 阅读全文
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Max Sum Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 65536/32768 K (Java/Others)Total Submission(s): 211310 Accepted Submission(s): 49611 Prob 阅读全文
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A + B Problem Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 65536/32768 K (Java/Others)Total Submission(s): 571020 Accepted Submission(s): 1811 阅读全文
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A + B Problem II Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 65536/32768 K (Java/Others)Total Submission(s): 310717 Accepted Submission(s): 6 阅读全文
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Problem Description Many years ago , in Teddy’s hometown there was a man who was called “Bone Collector”. This man like to collect varies of bones , s 阅读全文
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问题描述： 有n阶楼梯，每次只能迈一步或两步，输出有多少种迈法到达楼顶。 解题心得： 递归方法：先考虑最后一步，可能是迈了一步，可能是迈了两步。所以step(n)=step(n-1)+step(n-2)，然后step(0)=1，step(1)=1; 但是递归方法时间复杂度太高，n=40就已经需要一段 阅读全文
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题目描述 Most of you have played card games (and if you haven’t, why not???) in which the deck of cards is randomized by shuffling it one or more times.A p 阅读全文
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题目描述 “What a boring world!”Julyed felt so bored that she began to write numbers on the coordinate paper. She wrote a “0” on the center, then wrote the 阅读全文
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题目描述 Jack and Jill developed a special encryption method, so they can enjoy conversations without worrrying about eavesdroppers. Here is how: let L be 阅读全文