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Cutting an integer means to cut a K digits lone integer Z into two integers of (K/2) digits long integers A and B. For example, after cutting Z = 1673 阅读全文
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In the big cities, the subway systems always look so complex to the visitors. To give you some sense, the following figure shows the map of Beijing su 阅读全文
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Given a syntax tree (binary), you are supposed to output the corresponding infix expression, with parentheses reflecting the precedences of the operat 阅读全文
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Recommendation system predicts the preference that a user would give to an item. Now you are asked to program a very simple recommendation system that 阅读全文
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The "eight queens puzzle" is the problem of placing eight chess queens on an 8×8 chessboard so that no two queens threaten each other. Thus, a solutio 阅读全文
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Suppose that all the keys in a binary tree are distinct positive integers. A unique binary tree can be determined by a given pair of postorder and ino 阅读全文
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In graph theory, an Eulerian path is a path in a graph which visits every edge exactly once. Similarly, an Eulerian circuit is an Eulerian path which 阅读全文
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Given some segments of rope, you are supposed to chain them into one rope. Each time you may only fold two segments into loops and chain them into one 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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An AVL tree is a self-balancing binary search tree. In an AVL tree, the heights of the two child subtrees of any node differ by at most one; if at any 阅读全文