随笔分类 - PAT
摘要：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
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摘要：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
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摘要：The "eight queens puzzle" is the problem of placing eight chess queens on an 8 chessboard so that no two queens threaten each other. Thus, a solution
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摘要：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
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摘要：Given a syntax tree (binary), you are supposed to output the corresponding infix expression, with parentheses reflecting the precedences of the operat
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摘要：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
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摘要：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
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摘要：Given a singly linked list, you are supposed to rearrange its elements so that all the negative values appear before all of the non-negatives, and all
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摘要：A vertex cover of a graph is a set of vertices such that each edge of the graph is incident to at least one vertex of the set. Now given a graph with
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摘要：There is a kind of balanced binary search tree named red-black tree in the data structure. It has the following 5 properties: (1) Every node is either
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摘要：Consider a positive integer N written in standard notation with k+1 digits ai as ak⋯a1a0 with 0 for all i and ak>0. Then N is palindrom
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摘要：For a student taking the online course "Data Structures" on China University MOOC (http://www.icourse163.org/), to be qualified for a certificate, he/
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摘要：Suppose that all the keys in a binary tree are distinct positive integers. Given the preorder and inorder traversal sequences, you are supposed to out
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摘要：Unlike in nowadays, the way that boys and girls expressing their feelings of love was quite subtle in the early years. When a boy A had a crush on a g
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摘要：Look-and-say sequence is a sequence of integers as the following: D, D1, D111, D113, D11231, D112213111, ... where D is in [0, 9] except 1. The (n+1)s
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摘要：After each PAT, the PAT Center will announce the ranking of institutions based on their students' performances. Now you are asked to generate the rank
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摘要：A clique is a subset of vertices of an undirected graph such that every two distinct vertices in the clique are adjacent. A maximal clique is a clique
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摘要：The lowest common ancestor (LCA) of two nodes U and V in a tree is the deepest node that has both U and V as descendants. A binary search tree (BST) i
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摘要：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
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摘要：The task of this problem is simple: insert a sequence of distinct positive integers into a hash table first. Then try to find another sequence of inte
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