【C++ Primer Plus】编程练习答案——第16章
1 // chapter16.h 2 3 4 #ifndef LEARN_CPP_CHAPTER16_H 5 #define LEARN_CPP_CHAPTER16_H 6 7 #include <iostream> 8 #include <string> 9 #include <cctype> 10 #include <vector> 11 #include <ctime> 12 #include <cstdlib> 13 #include <fstream> 14 #include <algorithm> 15 #include <queue> 16 #include <list> 17 #include <memory> 18 19 void ch16_1(); 20 void ch16_2(); 21 void ch16_3(); 22 int reduce(long * ar, int n); 23 void ch16_4(); 24 template<class T> 25 int reduce2(T * ar, int n); 26 void ch16_5(); 27 bool newcustomer(double x); 28 void ch16_6(); 29 std::vector<int> lotto(int n, int select); 30 void ch16_7(); 31 void ch16_8(); 32 void ch16_9(); 33 34 struct Review { 35 std::string title; 36 int rating; 37 }; 38 bool operator<(const Review & r1, const Review & r2); 39 bool worseThan(const Review & r1, const Review & r2); 40 bool FillReview(Review & rr); 41 void ShowReview(const std::shared_ptr <Review> & rr); 42 void ch16_10(); 43 44 #endif //LEARN_CPP_CHAPTER16_H
1 // chapter16.cpp 2 3 4 #include "chapter16.h" 5 6 void ch16_1() { 7 using namespace std; 8 string str; 9 cout << "input a string: "; 10 getline(cin, str); 11 bool flag = true; 12 for (int i = 0; i < str.size() / 2; ++ i) 13 if (str[i] != str[str.size() - 1 - i]) { 14 flag = false; break; 15 } 16 cout << (flag ? "yes!" : "no!") << endl; 17 } 18 19 void ch16_2() { 20 using namespace std; 21 string str; 22 cout << "input a string: "; 23 getline(cin, str); 24 bool flag = true; 25 for (int i = 0, j = str.size() - 1; i < j; ++ i, -- j) { 26 if (!isalpha(str[i])) 27 ++i; 28 if (!isalpha(str[j])) 29 --j; 30 if (i < j) { 31 str[i] = tolower(str[i]); 32 str[j] = tolower(str[j]); 33 if (str[i] != str[j]) { 34 cout << str[i] << " " << str[j] << endl; 35 flag = false; 36 break; 37 } 38 } 39 } 40 cout << (flag ? "yes!" : "no!") << endl; 41 } 42 43 void ch16_3() { 44 using namespace std; 45 const string FILENAME = "../C++PrimerPlus/testfiles/hangman.txt"; 46 ifstream InFile; 47 InFile.open(FILENAME); 48 if (!InFile.is_open()) { 49 cout << "file not found" << endl; 50 return; 51 } 52 vector<string> wordlist; 53 string t; 54 while (InFile >> t) { 55 wordlist.push_back(t); 56 t = ""; 57 } 58 InFile.close(); 59 srand(time(0)); 60 char play; 61 cout << "Will you play a word game? <y/n> "; 62 cin >> play; 63 play = tolower(play); 64 while (play == 'y') { 65 string target = wordlist[rand() % wordlist.size()]; 66 int length = target.length(); 67 string attempt(length, '-'); 68 string badchars; 69 int guesses = 6; 70 cout << "Guess my secret word. It has " << length 71 << " letters, and you guess\n" 72 << "one letter at a time. You get " << guesses 73 << " wrong guesses." << endl; 74 cout << "Your word: " << attempt << endl; 75 while (guesses > 0 && attempt != target) { 76 char letter; 77 cout << "Guess a letter: "; 78 cin >> letter; 79 if (badchars.find(letter) != string::npos || attempt.find(letter) != string::npos) { 80 cout << "You already guessed that. Try again." << endl; 81 continue; 82 } 83 int loc = target.find(letter); 84 if (loc == string::npos) { 85 cout << "Oh, bad guess!" << endl; 86 -- guesses; 87 badchars += letter; 88 } 89 else { 90 cout << "Good guess!" << endl; 91 attempt[loc] = letter; 92 loc = target.find(letter, loc + 1); 93 while (loc != string::npos) { 94 attempt[loc] = letter; 95 loc = target.find(letter, loc + 1); 96 } 97 } 98 cout << "Your word: " << attempt << endl; 99 if (attempt != target) { 100 if (badchars.length() > 0) 101 cout << "Bad choices: " << badchars << endl; 102 cout << guesses << " bad guesses left" << endl; 103 } 104 } 105 if (guesses > 0) 106 cout << "That's right!" << endl; 107 else 108 cout << "Sorry, the word is " << target << "." << endl; 109 cout << "Will you play another? <y/n> "; 110 cin >> play; 111 play = tolower(play); 112 } 113 cout << "Bye! " << endl; 114 } 115 116 int reduce(long * ar, int n) { 117 std::sort(ar, ar + n); 118 long * end = std::unique(ar, ar + n); 119 return int(end - ar); 120 } 121 122 void ch16_4() { 123 using namespace std; 124 long arr[5] = {3, 9, 0, 1, 1}; 125 for (auto x : arr) 126 cout << x << "\t"; 127 cout << endl; 128 int l = reduce(arr, 5); 129 for (int i = 0; i < l; ++ i) 130 cout << arr[i] << "\t"; 131 cout << endl; 132 } 133 134 template<class T> 135 int reduce2(T * ar, int n) { 136 std::sort(ar, ar + n); 137 T * end = std::unique(ar, ar + n); 138 return int(end - ar); 139 } 140 141 void ch16_5() { 142 using namespace std; 143 long arr[5] = {3, 9, 0, 1, 1}; 144 for (auto x : arr) 145 cout << x << "\t"; 146 cout << endl; 147 int l = reduce2(arr, 5); 148 for (int i = 0; i < l; ++ i) 149 cout << arr[i] << "\t"; 150 cout << endl; 151 string arr2[5] = {"bb", "aa", "cc", "cc", "cc"}; 152 for (auto x : arr2) 153 cout << x << "\t"; 154 cout << endl; 155 int l2 = reduce2(arr2, 5); 156 for (int i = 0; i < l2; ++ i) 157 cout << arr2[i] << "\t"; 158 cout << endl; 159 } 160 161 const int MIN_PER_HR = 60; 162 163 bool newcustomer(double x) { 164 return (std::rand() * x / RAND_MAX < 1); 165 } 166 167 void ch16_6() { 168 // 懒得打字了，很简单。。 169 } 170 171 std::vector<int> lotto(int n, int select) { 172 std::vector<int> arr(n); 173 for (int i = 1; i <= n; ++ i) 174 arr[i - 1] = i; 175 std::vector<int> winner; 176 srand(unsigned(time(0))); 177 for (int i = 0; i < select; ++ i) { 178 std::random_shuffle(arr.begin() + i, arr.end()); 179 winner.push_back(arr[i]); 180 } 181 return winner; 182 } 183 184 void ch16_7() { 185 using namespace std; 186 int n, select; 187 cout << "game!" << endl; 188 cout << "input num: "; cin >> n; 189 cout << "input select num: "; cin >> select; 190 cout << "result: " << endl; 191 for (auto x : lotto(n, select)) 192 cout << x << "\t"; 193 cout << endl; 194 } 195 196 void ch16_8() { 197 using namespace std; 198 vector<string> mat, pat; 199 string t; 200 cout << "Hey Mat, who do you want to invite <end to quit>:" << endl; 201 while (getline(cin, t)) { 202 if (t == "end") 203 break; 204 mat.push_back(t); 205 t = ""; 206 //cin.get(); 207 } 208 cout << "Hey Pat, who do you want to invite <end to quit>:" << endl; 209 while (getline(cin, t)) { 210 if (t == "end") 211 break; 212 pat.push_back(t); 213 t = ""; 214 //cin.get(); 215 } 216 sort(mat.begin(), mat.end()); 217 sort(pat.begin(), pat.end()); 218 cout << "Mat's guests: "; 219 for (auto x : mat) 220 cout << x << " "; 221 cout << endl << "Pat's guests: "; 222 for (auto x : pat) 223 cout << x << " "; 224 vector<string> mer(mat.size() + pat.size()); 225 merge(mat.begin(), mat.end(), pat.begin(), pat.end(), mer.begin()); 226 cout << endl << "All guests: "; 227 for (auto x : mer) 228 cout << x << " "; 229 cout << endl; 230 } 231 232 void ch16_9() { 233 using namespace std; 234 vector<int> vi0(10000000); 235 vector<int> vi(10000000); 236 list<int> li(10000000); 237 srand(unsigned(time(0))); 238 for (auto x : vi0) 239 x = rand(); 240 copy(vi0.begin(), vi0.end(), vi.begin()); 241 copy(vi0.begin(), vi0.end(), li.begin()); 242 clock_t vit, lit, lit2, start, end; 243 244 start = clock(); 245 sort(vi.begin(), vi.end()); 246 end = clock(); 247 vit = end - start; 248 249 start = clock(); 250 li.sort(); 251 end = clock(); 252 lit = end - start; 253 254 copy(vi0.begin(), vi0.end(), li.begin()); 255 start = clock(); 256 copy(li.begin(), li.end(), vi.begin()); 257 sort(vi.begin(), vi.end()); 258 copy(vi.begin(), vi.end(), li.begin()); 259 end = clock(); 260 lit2 = end - start; 261 262 cout << "<10000000 int nums for sort>" << endl; 263 cout << "vector sort time: " << double(vit) / CLOCKS_PER_SEC << " secs" << endl; 264 cout << "list sort time: " << double(lit) / CLOCKS_PER_SEC << " secs" << endl; 265 cout << "list -> vector, vector sort, vector -> list time: " << double(lit2) / CLOCKS_PER_SEC << " secs" << endl; 266 } 267 268 bool operator<(const Review & r1, const Review & r2) { 269 if (r1.title < r2.title) 270 return true; 271 else if (r1.title == r2.title && r1.rating < r2.rating) 272 return true; 273 else 274 return false; 275 } 276 277 bool worseThan(const Review & r1, const Review & r2) { 278 if (r1.rating < r2.rating) 279 return true; 280 else 281 return false; 282 } 283 284 bool FillReview(Review & rr) { 285 std::cout << "Enter book title (quit to quit): "; 286 std::getline(std::cin, rr.title); 287 if (rr.title == "quit") 288 return false; 289 std::cout << "Enter book rating: "; 290 std::cin >> rr.rating; 291 if (!std::cin) 292 return false; 293 while (std::cin.get() != '\n') 294 continue; 295 return true; 296 } 297 298 void ShowReview(const std::shared_ptr <Review> & rr) { 299 std::cout << rr -> rating << "\t" << rr -> title << std::endl; 300 } 301 302 void ch16_10() { 303 using namespace std; 304 vector<shared_ptr<Review>> books; 305 shared_ptr<Review> t; 306 Review temp; 307 while (FillReview(temp)) 308 books.push_back(static_cast<shared_ptr <Review>>(new Review(temp))); 309 if (books.size() > 0) { 310 cout << "Thank you. You entered the following " 311 << books.size() << " ratings:" << endl 312 << "Rating\tBook\n"; 313 for_each(books.begin(), books.end(), ShowReview); 314 315 sort(books.begin(), books.end()); 316 cout << "Sorted by title:\nRating\tBook\n"; 317 for_each(books.begin(), books.end(), ShowReview); 318 319 random_shuffle(books.begin(), books.end()); 320 cout << "After shuffling:\nRating\tBook\n"; 321 for_each(books.begin(), books.end(), ShowReview); 322 } 323 else 324 cout << "No entries. "; 325 cout << "Bye!" << endl; 326 }
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