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A Binary Search Tree (BST) is recursively defined as a binary tree which has the following properties:The left subtree of a node contains only nodes with keys less than the node's key. The right su...

Input our current position and a destination, an online map can recommend several paths. Now your job is to recommend two paths to your user: one is the shortest, and the other is the fastest. It is g...

Given a non-empty tree with rootR, and with weightW​i​​assigned to each tree nodeT​i​​. Theweight of a path fromRtoLis defined to be the sum of the weights of all the nodes along the path fro...

One way that the police finds the head of a gang is to check people's phone calls. If there is a phone call betweenAandB, we say thatAandBis related. The weight of a relation is defined to be t...

A graph which is connected and acyclic can be considered a tree. The height of the tree depends on the selected root. Now you are supposed to find the root that results in a highest tree. Such a root ...

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 time they differ by more than one, rebalancing is...

The "Hamilton cycle problem" is to find a simple cycle that contains every vertex in a graph. Such a cycle is called a "Hamiltonian cycle".In this problem, you are supposed to tell if a given cycle ...

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 starts and ends on the same vertex. They were firs...

An inorder binary tree traversal can be implemented in a non-recursive way with a stack. For example, suppose that when a 6-node binary tree (with the keys numbered from 1 to 6) is traversed, the stac...

A supply chain is a network of retailers（零售商）, distributors（经销商）, and suppliers（供应商）-- everyone involved in moving a product from supplier to customer.Starting from one root supplier, everyone on th...

Given a syntax tree (binary), you are supposed to output the corresponding infix expression, with parentheses reflecting the precedences of the operators.Input Specification:Each input file contai...

A supply chain is a network of retailers（零售商）, distributors（经销商）, and suppliers（供应商）-- everyone involved in moving a product from supplier to customer.Starting from one root supplier, everyone on th...

Werewolf（狼人杀） is a game in which the players are partitioned into two parties: the werewolves and the human beings. Suppose that in a game,player #1 said: "Player #2 is a werewolf."; player #2 said...

The "travelling salesman problem" asks the following question: "Given a list of cities and the distances between each pair of cities, what is the shortest possible route that visits each city and retu...

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.Given any two nodes in a binary tree, you are supposed to find their LCA.In...

Suppose that all the keys in a binary tree are distinct positive integers. Given the preorder and inorder traversal sequences, you are supposed to output the first number of the postorder traversal se...

The following is from Max Howell @twitter:Google: 90% of our engineers use the software you wrote (Homebrew), but you can't invert a binary tree on a whiteboard so fuck off.Now it's your turn to...

A supply chain is a network of retailers（零售商）, distributors（经销商）, and suppliers（供应商）-- everyone involved in moving a product from supplier to customer.Starting from one root supplier, everyone on th...

A Binary Search Tree (BST) is recursively defined as a binary tree which has the following properties:The left subtree of a node contains only nodes with keys less than or equal to the node's key. ...

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 inorder traversal sequences, or preorder and inorder ...

Given a tree, you are supposed to tell if it is a complete binary tree.Input Specification:Each input file contains one test case. For each case, the first line gives a positive integerN(≤20) wh...

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 inorder traversal sequences. And it is a simple stand...

Eva loves to collect coins from all over the universe, including some other planets like Mars. One day she visited a universal shopping mall which could accept all kinds of coins as payments. However,...

Eva is trying to make her own color stripe out of a given one. She would like to keep only her favorite colors in her favorite order by cutting off those unwanted pieces and sewing the remaining parts...

Given a string, you are supposed to output the length of the longest symmetric sub-string. For example, givenIs PAT&TAP symmetric?, the longest symmetric sub-string iss PAT&TAP s, hence you ...

There is a kind of balanced binary search tree namedred-black treein the data structure. It has the following 5 properties:(1) Every node is either red or black. (2) The root is black. (3) Every...

In computer science, aheapis a specialized tree-based data structure that satisfies the heap property: if P is a parent node of C, then the key (the value) of P is either greater than or equal to (i...

Suppose that all the keys in a binary tree are distinct positive integers. Given the postorder and inorder traversal sequences, you are supposed to output the level order traversal sequence of the cor...

A Binary Search Tree (BST) is recursively defined as a binary tree which has the following properties:The left subtree of a node contains only nodes with keys less than the node's key. The right su...

A family hierarchy is usually presented by a pedigree tree where all the nodes on the same level belong to the same generation. Your task is to find the generation with the largest population.Input ...

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. Given the records of signing in's and out's, you...

Given any string ofN(≥5) characters, you are asked to form the characters into the shape ofU. For example,helloworldcan be printed as:h de ll rlowoThat is, the characters must be prin...

People in Mars represent the colors in their computers in a similar way as the Earth people. That is, a color is represented by a 6-digit number, where the first 2 digits are forRed, the middle 2 dig...

There is a public bike service in Hangzhou City which provides great convenience to the tourists from all over the world. One may rent a bike at any station and return it to any other stations in the ...

Notice that the number 123456789 is a 9-digit number consisting exactly the numbers from 1 to 9, with no duplication. Double it we will obtain 246913578, which happens to be another 9-digit number con...

A number that will be the same when it is written forwards or backwards is known as aPalindromic Number. For example, 1234321 is a palindromic number. All single digit numbers are palindromic numbers...

The task is really simple: givenNexits on a highway which forms a simple cycle, you are supposed to tell the shortest distance between any pair of exits.Input Specification:Each input file conta...

Given a sequence ofKintegers {N​1​​,N​2​​, ...,N​K​​}. A continuous subsequence is defined to be {N​i​​,N​i+1​​, ...,N​j​​} where1≤i≤j≤K. The Maximum Subsequence is the continuous subsequen...

Suppose a bank hasNwindows open for service. There is a yellow line in front of the windows which devides the waiting area into two parts. The rules for the customers to wait in line are:The space...

Areversible primein 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 reversible prime because its reverse 37 is also a pr...