程式設計-小專題-電子雞自己猜數字
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我的想法:二分法
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利用二分法的原理，設定最大值與最小值，然後利用公式(max+min)/2的結果來當作每次猜測的值，範圍在最大值與最小值之間，最後猜出正確答案。

  // Randomly generate numbers between 1 and 1000 for user to guess.
#include <stdio.h>
#include <stdlib.h>
#include <time.h>

void guessGame(void); // function prototype
int isCorrect(int, int); // function prototype

int main(void)
{
   // srand( time( 0 ) ); // seed random number generator
   guessGame();
} // end main

// guessGame generates numbers between 1 and 1000
// and checks user's guess
void guessGame(void)
{
   int answer; // randomly generated number
   int guess; // user's guess
   int response; // 1 or 2 response to continue game
   int i = 1;
   // loop until user types 2 to quit game
   do {
      
      int min = 1,max = 1000;
      // generate random number between 1 and 1000
      // 1 is shift, 1000 is scaling factor
      answer = 1 + rand() % 1000;

      // prompt for guess
      puts("I have a number between 1 and 1000.\n" 
           "Can you guess my number?\n" 
           "Please type your first guess.");
      printf("%s", "? ");
      guess = (min + max) / 2;
      printf("%d\n",guess);

      // loop until correct number
      while (!isCorrect(guess, answer)) 
         {
            if (guess < answer)
            {
                min = guess + 1;
                guess = (min + max) / 2;
                printf("%d\n",guess);
            }
            else if (guess > answer)
            {
                max = guess - 1;
                guess = (min + max) / 2;
                printf("%d\n",guess);
            }
            i++;
         }
            printf("guess %d times\n", i);
      // prompt for another game
      puts("\nExcellent! You guessed the number!\n"
         "Would you like to play again?");
      printf("               , ,  \n");
printf("              /| |\\     \n" );
printf("             / | | \\    \n");
printf("             | | | |      \n");
printf("             \\ | | /      \n");
printf("              \\|w|/    /    \n");
printf("              /_ _\\   /      ,\n");
printf("   /\\       _:()_():_       /]       \n");
printf("   ||_     : ._=Y=_  :     / /   \n");
printf("  [)(_\\,   ',__\\W/ _,'    /  \\    \n");
printf("  [) \\_/\\    _/'='\\      /-/\\)   \n");
printf("   [_| \\ \\  ///  \\ '._  / /     \n");
printf("   :;   \\ \\///   / |  '` /     \n");
printf("   ;::   \\ `|:   : |',_.'    \n" );   
printf("   ""'    \\_|:   : |  \n");
printf("            |:   : |''.    \n");
printf("            /`._.'  \\/  \n");
printf("           /  /|   /   \n");
printf("          |  \\ /  /   \n");
printf("           '. '. /     \n");
printf("             '. '      \n");
printf("             / \\ \\       \n");
printf("            / / \'=,      \n");
printf("      .----' /   \\ (\\__      \n");
printf(" snd (((____/     \\ \\  )     \n");
printf("                   '.\\_)     \n");   
      printf("%s", "Please type ( 1=yes, 2=no )? ");
      scanf("%d", &response);

      puts("");
   } while (response == 1);
} // end function guessGame

// isCorrect returns true if g equals a
// if g does not equal a, displays hint
int isCorrect(int g, int a)
{
   // guess is correct
   if (g == a)
      return 1;

   // guess is incorrect; display hint
   if (g < a)
      printf( "%s", "Too low. Try again.\n? " );
   else
      printf( "%s", "Too high. Try again.\n? " );

   return 0;
} // end function isCorrect