7.CSharpAdvancedTopics:C# 中的程序

Homework: C# Advanced Topics This document defines the homework assignments from the “C# Basics“ Course @ Software University. Problem 1. Fibonacci Numbers Define a method Fib(n) that calculates the nth Fibonacci number. Examples: n Fib(n) 0 1 1 1 2 2 3 3 4 5 5 8 6 13 11 144 25 121393 Problem 2. Prime Checker Write a Boolean method IsPrime(n) that check whether a given integer number n is prime. Examples: n IsPrime(n) 0 false 1 false 2 true 3 true 4 false 5 true 323 false 337 true 6737626471 true 117342557809 false Problem 3. Primes in Given Range Write a method that calculates all prime numbers in given range and returns them as list of integers: static List<int> FindPrimesInRange(startNum, endNum) { … } Write a method to print a list of integers. Write a program that enters two integer numbers (each at a separate line) and prints all primes in their range, separated by a comma. Examples: Start number End number Output 0 10 2, 3, 5, 7 5 11 5, 7, 11 100 200 101, 103, 107, 109, 113, 127, 131, 137, 139, 149, 151, 157, 163, 167, 173, 179, 181, 191, 193, 197, 199 250 950 251, 257, 263, 269, 271, 277, 281, 283, 293, 307, 311, 313, 317, 331, 337, 347, 349, 353, 359, 367, 373, 379, 383, 389, 397, 401, 409, 419, 421, 431, 433, 439, 443, 449, 457, 461, 463, 467, 479, 487, 491, 499, 503, 509, 521, 523, 541, 547, 557, 563, 569, 571, 577, 587, 593, 599, 601, 607, 613, 617, 619, 631, 641, 643, 647, 653, 659, 661, 673, 677, 683, 691, 701, 709, 719, 727, 733, 739, 743, 751, 757, 761, 769, 773, 787, 797, 809, 811, 821, 823, 827, 829, 839, 853, 857, 859, 863, 877, 881, 883, 887, 907, 911, 919, 929, 937, 941, 947 100 50 (empty list) Problem 4. Difference between Dates Write a program that enters two dates in format dd.MM.yyyy and returns the number of days between them. Examples: First date Second date Days between 17.03.2014 30.04.2014 44 17.03.2014 17.03.2014 0 14.06.1980 5.03.2014 12317 5.03.2014 3.03.2014 -2 Problem 5. Sorting Numbers Write a program that reads a number n and a sequence of n integers, sorts them and prints them. Examples: Input Output 5 3 -3 2 122 0 -3 0 2 3 122 3 0 1 0 0 0 1 Problem 6. Longest Area in Array Write a program to find the longest area of equal elements in array of strings. You first should read an integer n and n strings (each at a separate line), then find and print the longest sequence of equal elements (first its length, then its elements). If multiple sequences have the same maximal length, print the leftmost of them. Examples: Input Output 6 hi hi hello ok ok ok 3 ok ok ok 2 SoftUni Hello 1 SoftUni 4 hi hi hi hi 4 hi hi hi hi 5 wow hi hi ok ok 2 hi hi Problem 7. Matrix of Palindromes Write a program to generate the following matrix of palindromes of 3 letters with r rows and c columns: Input Output 3 6 aaa aba aca ada aea afa bbb bcb bdb beb bfb bgb ccc cec cdc cfc cgc chc 2 3 aaa aba aca bbb bcb bdb 1 1 aaa 1 3 aaa aba aca Problem 8. * Longest Non-Decreasing Subsequence Write a program that reads a sequence of integers and finds in it the longest non-decreasing subsequence. In other words, you should remove a minimal number of numbers from the starting sequence, so that the resulting sequence is non-decreasing. In case of several longest non-decreasing sequences, print the leftmost of them. The input and output should consist of a single line, holding integer numbers separated by a space. Examples: Input Output 1 1 7 3 5 8 -1 6 7 3 5 6 7 1 1 1 2 2 2 1 1 1 1 1 1 3 3 3 2 2 2 2 2 2 2 2 11 12 13 3 14 4 15 5 6 7 8 7 16 9 8 3 4 5 6 7 8 9 Problem 9. Remove Names Write a program that takes as input two lists of names and removes from the first list all names given in the second list. The input and output lists are given as words, separated by a space, each list at a separate line. Examples: Input Output Peter Alex Maria Todor Steve Diana Steve Todor Steve Nakov Peter Alex Maria Diana Hristo Hristo Nakov Nakov Petya Nakov Vanessa Maria Hristo Hristo Petya Problem 10. Join Lists Write a program that takes as input two lists of integers and joins them. The result should hold all numbers from the first list, and all numbers from the second list, without repeating numbers, and arranged in increasing order. The input and output lists are given as integers, separated by a space, each list at a separate line. Examples: Input Output 20 40 10 10 30 80 25 20 40 30 10 10 20 25 30 40 80 5 4 3 2 1 6 3 2 1 2 3 4 5 6 1 1 1 Problem 11. Count of Letters Write a program that reads a list of letters and prints for each letter how many times it appears in the list. The letters should be listed in alphabetical order. Use the input and output format from the examples below. Examples: Input Output b b a a b a -> 2 b -> 3 h d h a a a s d f d a d j d s h a a a -> 6 d -> 5 f -> 1 h -> 3 j -> 1 s -> 2 Problem 12. Count of Names Write a program that reads a list of names and prints for each name how many times it appears in the list. The names should be listed in alphabetical order. Use the input and output format from the examples below. Examples: Input Output Peter Steve Nakov Steve Alex Nakov Alex -> 1 Nakov -> 2 Peter -> 1 Steve -> 2 Nakov Nakov Nakov SoftUni Nakov SoftUni -> 1 Nakov -> 5 Problem 13. Average Load Time Calculator We have a report that holds dates, web site URLs and load times (in seconds) in the same format like in the examples below. Your tasks is to calculate the average load time for each URL. Print the URLs in the same order as they first appear in the input report. Print the output in the format given below. Use double floating-point precision. Examples: Input Output 2014-Mar-02 11:33 http://softuni.bg 8.37725 2014-Mar-02 11:34 http://www.google.com 1.335 2014-Mar-03 21:03 http://softuni.bg 7.25 2014-Mar-03 22:00 http://www.google.com 2.44 2014-Mar-03 22:01 http://www.google.com 2.45 2014-Mar-03 22:01 http://www.google.com 2.77 http://softuni.bg -> 7.813625 http://www.google.com -> 2.24875 2014-Apr-01 02:01 http://softuni.bg 8.37725 2014-Apr-01 02:05 http://www.nakov.com 11.622 2014-Apr-01 02:06 http://softuni.bg 4.33 2014-Apr-01 02:11 http://www.google.com 1.94 2014-Apr-01 02:11 http://www.google.com 2.011 2014-Apr-01 02:12 http://www.google.com 4.882 2014-Apr-01 02:34 http://softuni.bg 4.885 2014-Apr-01 02:36 http://www.nakov.com 10.74 2014-Apr-01 02:36 http://www.nakov.com 11.75 2014-Apr-01 02:38 http://softuni.bg 3.886 2014-Apr-01 02:44 http://www.google.com 1.04 2014-Apr-01 02:48 http://www.google.com 1.4555 2014-Apr-01 02:55 http://www.google.com 1.977 http://softuni.bg -> 5.3695625 http://www.nakov.com -> 11.3706666666667 http://www.google.com -> 2.21758333333333 Problem 14. Longest Word in a Text Write a program to find the longest word in a text. Examples: Input Output Welcome to the Software University. University The C# Basics course is awesome start in programming with C# and Visual Studio. programming Problem 15. Extract URLs from Text Write a program that extracts and prints all URLs from given text. URL can be in only two formats: • http://something, e.g. http://softuni.bg, http://forums.softuni.bg, http://www.nakov.com • www.something.domain, e.g. www.nakov.com, www.softuni.bg, www.google.com Examples: Input Output The site nakov.com can be access from http://nakov.com or www.nakov.com. It has subdomains like mail.nakov.com and svetlin.nakov.com. Please check http://blog.nakov.com for more information. http://nakov.com www.nakov.com http://blog.nakov.com Problem 16. * Counting a Word in a Text Write a program that counts how many times a given word occurs in given text. The first line in the input holds the word. The second line of the input holds the text. The output should be a single integer number – the number of word occurrences. Matching should be case-insensitive. Note that not all matching substrings are words and should be counted. A word is a sequence of letters separated by punctuation or start / end of text. Examples: Input Output hi Hidden networks say “Hi” only to Hitachi