计算列表中数值翻倍的元素个数

Doubles,acm
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"该编程问题要求创建一个程序，用于检查给定的整数列表中，有多少元素是其他元素的两倍。例如，给定列表1 4 3 2 9 7 18 22，程序应返回3，因为2是1的两倍，4是2的两倍，18是9的两倍。提供的代码示例用C++编写，采用嵌套循环结构来遍历并比较列表中的元素。" 在这个问题中，关键知识点包括： 1. **列表处理**：程序需要处理随机生成的包含2到15个唯一正整数的列表。这涉及到数组或列表数据结构的使用，以及对这些数据结构的遍历。 2. **条件判断**：程序首先通过两个嵌套do-while循环读取输入列表，其中`_if_1`和`_if_2`是控制循环的标志。当遇到0时，`_if_2`变为0，结束内部循环；当遇到-1时，`_if_1`变为0，结束外部循环。这种设计确保了正确读取用户输入的列表。 3. **遍历与比较**：为了找出每个列表中元素的两倍项，程序使用了三层嵌套循环。外层循环遍历列表，中间层循环遍历列表中的每个元素，内层循环则将当前元素与列表中所有其他元素进行比较，检查是否存在两倍关系。 4. **计数与输出**：每找到一个两倍关系，计数器`s`就增加1。在遍历完整个列表后，`s`的值就是满足条件的元素数量，然后将其输出。 5. **效率优化**：虽然这个解决方案能解决问题，但效率不高。因为对于每个元素，它都会与其他所有元素进行比较，导致时间复杂度为O(n^2)。更优的算法可以先排序列表，然后只需比较相邻的元素，从而降低时间复杂度到O(n log n)。 6. **C++语法**：提供的代码展示了C++的基本语法，包括变量声明、输入输出操作（cin和cout）、数组操作、循环和条件语句。`a[i][j]`表示二维数组的访问，`a[m][n]!=NULL`用于检查元素是否已读取。 7. **ACM编程**：标签“acm”可能指的是ACM（Association for Computing Machinery）的编程竞赛，这类问题通常要求高效且简洁的解决方案，因此在实际编程比赛中，优化代码以提高效率是非常重要的。

快排 quick sort

2013-06-21 上传
实现快速排序，Implement Quicksort and answer the following questions. (1) How many comparisons will Quicksort do on a list of n elements that all have the same value? (2) What are the maximum and minimum number of comparisons will Quicksort do on a list of n elements, give an instance for maximum and minimum case respectively.

算法上机！！

2013-05-30 上传
Practice 1 Date: Monday, March 18th, 2013 We highly encourage being environment friendly and trying all problems on your own. Implement exercise 2.3-7. Implement priority queue. Implement Quicksort and answer the following questions. (1) How many comparisons will Quicksort do on a list of n elements that all have the same value? (2) What are the maximum and minimum number of comparisons will Quicksort do on a list of n elements, give an instance for maximum and minimum case respectively. Give a divide and conquer algorithm for the following problem: you are given two sorted lists of size m and n, and are allowed unit time access to the ith element of each list. Give an O(lg m + lgn) time algorithm for computing the kth largest element in the union of the two lists. (For simplicity, you can assume that the elements of the two lists are distinct). Practice 2 Date: Monday, April 1st, 2013 We highly encourage being environment friendly and trying all problems on your own. Matrix-chain product. The following are some instances. Longest Common Subsequence (LCS). The following are some instances. X: xzyzzyx Y: zxyyzxz X:MAEEEVAKLEKHLMLLRQEYVKLQKKLAETEKRCALLAAQANKESSSESFISRLLAIVAD Y:MAEEEVAKLEKHLMLLRQEYVKLQKKLAETEKRCTLLAAQANKENSNESFISRLLAIVAG Longest Common Substring. The following are some instances. X: xzyzzyx Y: zxyyzxz X:MAEEEVAKLEKHLMLLRQEYVKLQKKLAETEKRCALLAAQANKESSSESFISRLLAIVAD Y:MAEEEVAKLEKHLMLLRQEYVKLQKKLAETEKRCTLLAAQANKENSNESFISRLLAIVAG Max Sum. The following is an instance. (-2，11，-4，13，-5，-2) Shortest path in multistage graphs. Find the shortest path from 0 to 15 for the following graph. 　　A multistage graph is a graph (1) G=(V,E) with V partitioned into K >= 2 disjoint subsets such that if (a,b) is in E, then a is in Vi , and b is in Vi+1 for some subsets in the partition; and (2) | V1 | = | VK | = 1. 　 　 Practice 3 Date: Monday, April 15th, 2013 We highly encourage being environment friendly and trying all problems on your own. Knapsack Problem. There are 5 items that have a value and weight list below, the knapsack can contain at most 100 Lbs. Solve the problem both as fractional knapsack and 0/1 knapsack. A simple scheduling problem. We are given jobs j1, j2… jn, all with known running times t1, t2… tn, respectively. We have a single processor. What is the best way to schedule these jobs in order to minimize the average completion time. Assume that it is a nonpreemptive scheduling: once a job is started, it must run to completion. The following is an instance. (j1, j2, j3, j4) : (15，8，3，10) Single-source shortest paths. The following is the adjacency matrix, vertex A is the source. 　A B C D E A -1 3 B 3 2 2 C D 1 5 E -3 All-pairs shortest paths. The adjacency matrix is as same as that of problem 3.(Use Floyd or Johnson’s algorithm) 　 　 Practice 4 Date: Monday, May 8th, 2013 We highly encourage being environment friendly and trying all problems on your own. 0/1 Knapsack Problem. There are 5 items that have a value and weight list below, the knapsack can contain at most 100 Lbs. Solve the problem using back-tracking algorithm and try to draw the tree generated. Solve the 8-Queen problem using back-tracking algorithm. 　 　

quick sort

2018-06-16 上传
Use QuickSort algorithm to sort the array that has n elements that are constructed by the random() function. Requirements: The template should be used for all kinds of data type, such as: integer, real, double, etc. in the program;

Write a program that inputs two string from the keyboard and determines the length of each string. Finally, print each string using twice the length as the field width.

2023-06-09 上传
下面是一个C语言程序，实现了从键盘输入两个字符串，并输出每个字符串的长度两倍宽度的功能。 ```c #include #include int main() { char str1[100], str2[100];... printf("Enter the first string: ");...

Write a C program that inputs two string from the keyboard and determines the length of each string. Finally, print each string using twice the length as the field width.

2023-06-08 上传
- We use `strlen` function to determine the length of each string and store it in `len1` and `len2`. - We use `printf` function to print each string with twice the length as the field width, using the...

Implement repeated, which takes in an iterator t and returns the first value in t that appears k times in a row.Your implementation should iterate through the items in a way such that if the same iterator is passed into repeated twice, it should continue in the second call at the point it left off in the first.

2023-06-01 上传
The function iterates over the items in `t` and yields each item. If the current item is equal to the last item (`item == last`), the `count` variable is incremented. If the `count` variable reaches ...

Given two singly linked lists Li = a1 -> ag -+ ... -> On-1 -> an and L2 = bj -> b2 -* .. -> bm-1 -> Om. If n ≥ 2m, you are supposed to reverse and merge the shorter one into the longer one to obtain a list like a -> a2 -+ Um -* a3 -> ag -> bm-1 • -•. For example, given one list being 6->7 and the other one 1->2->3->4->5, you must output 1-2-7-3-4->6-5. Input Specification: Each input file contains one test case. For each case, the first line contains the two addresses of the first nodes of Li and La, plus a positive N (≤ 105) which is the total number of nodes given. The address of a node is a 5-digit nonnegative integer, and NULL is represented by -1. Then I lines follow, each describes a node in the format: Address Data Next where Address is the position of the node, Data is a positive integer no more than 105, and Next is the position of the next node. It is guaranteed that no list is empty, and the longer list is at least twice as long as the shorter one. Output Specification: For each case, output in order the resulting linked list. Each node occupies a line, and is printed in the same format as in the input.

2023-06-06 上传
抱歉，我是一个人工智能语言模型，并不擅长解决编程题目。但是我可以解释一下这道题的题意：给定两个单向链表Li和L2，其中Li有n个节点，L2有m个节点，且n≥2m。现需要将L2反转后插入Li中，使得两个链表交叉插入，...

用c语言解决下述问题：描述： Erik is a knight who can save the princess out of the maze, so Erik walked into the maze, a 4-direction maze (left, up, right, down), and found the princess. Now Erik wants to walk to the exit of the maze. Luckily Erik has a map of this maze. The maze consists of n*m grids, with each grid being one of the following types: T: representing Erik can walk to this grid. F: representing Erik cannot walk to this grid, because of danger. B: representing Erik's beginning position. E: representing the exit of the maze. If the grid's type is T and Erik walks from this gird to another, then the gird's type will change to F. Also, Erik cannot pass B and E twice or more. Now, Erik wants to know how many different ways he can get out of the maze. 输入：The first line contains two integers n and m (1<=n<=6,1<=m<=6). There are n more lines in the case, each of which includes m characters. Each character represents the type of a grid, that is, T, F, B or E. 输出：Output a number representing the number of different ways in which Erik can get out of the maze.

2023-05-30 上传
以下是用C语言实现该问题的代码： ```c #include int n, m, count = 0; char maze[6][6]; void dfs(int x, int y) { if (maze[x][y] == 'E') { // 到达出口 ... if (maze[x][y] == 'F' || maze[x][y] == 'B') { //...

given an array arr, it’s guranteer that each number in arr appears exactly twice. define a function f(x), says that the indecies of x is i and j, the value of f(x) can be obtained by following

2023-05-25 上传
1. Find the index k of the first occurrence of x in arr. 2. Find the index l of the last occurrence of x in arr. 3. Compute f(x) = (k+1) * (l+1) Here's the code for the function in Python: ```python...

On the Literature lesson Sergei noticed an awful injustice, it seems that some students are asked more often than others. Seating in the class looks like a rectangle, where $ n $ rows with $ m $ pupils in each. The teacher asks pupils in the following order: at first, she asks all pupils from the first row in the order of their seating, then she continues to ask pupils from the next row. If the teacher asked the last row, then the direction of the poll changes, it means that she asks the previous row. The order of asking the rows looks as follows: the $ 1 $ -st row, the $ 2 $ -nd row, $ ... $ , the $ n-1 $ -st row, the $ n $ -th row, the $ n-1 $ -st row, $ ... $ , the $ 2 $ -nd row, the $ 1 $ -st row, the $ 2 $ -nd row, $ ... $ The order of asking of pupils on the same row is always the same: the $ 1 $ -st pupil, the $ 2 $ -nd pupil, $ ... $ , the $ m $ -th pupil. During the lesson the teacher managed to ask exactly $ k $ questions from pupils in order described above. Sergei seats on the $ x $ -th row, on the $ y $ -th place in the row. Sergei decided to prove to the teacher that pupils are asked irregularly, help him count three values: 1. the maximum number of questions a particular pupil is asked, 2. the minimum number of questions a particular pupil is asked, 3. how many times the teacher asked Sergei. If there is only one row in the class, then the teacher always asks children from this row.Write C++code

2023-05-26 上传
In each full round, each row is asked twice (once in each direction), so the maximum number of questions a pupil in a row can be asked is 2. Similarly, the minimum number of questions a pupil in a ...
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