package numberguesser; import java.io.*; public class NumberGuesser { public NumberGuesser() { GuessNumber(); } public void GuessNumber() { BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); /* 90 holds the upper bound + 1 to output if the user makes an error */ int errorOutput; /* 91 used to divide the difference of lastGuess and currentGuess to add or subtract to/from next guess */ final int CONSTANT_2 = 2; /* 92 holds the 0, 1, 999 user input value */ int userInput = 0; /* 94 used to hold the value of the last guess */ int lastGuess = 0; /* 95 used to hold the value of the current guess */ int currentGuess = 0; /* 96 used to make negative differences positive */ final int CONSTANT_NEG_1 = -1; /* 97 temp storage to hold calculated differences */ int tempStorage; /* 89 counts the number of errors before telling the user he/she has made a miscalculation (must equal 14 to cause output of errorOutput because this is the number it takes to reach 0 when having an upper bound of 100,000,000 */ int errorCounter = 0; int axRegister; System.out.print("? "); /* 0 - 7 This segment of the code takes in the upper bound, adds 1 to the value and stores it in "errorOutput" to display if a user error is made. */ try { currentGuess = Integer.parseInt(br.readLine()); } catch (IOException e) { e.printStackTrace(); } errorOutput = currentGuess + 1; //////////////////////////////////////////////////////////////////////// /* This loop represents the loop that the assembly program follows each time a guess is presented to the user. */ while (true) { /* 8 - 11 Loads the currentGuess and subtracts the last guess to either add or subtract half of the difference for the next guess. */ axRegister = currentGuess; axRegister -= lastGuess; //////////////////////////////////////////////////////////////////////// /* 12 - 15 If the value in the axRegister is negative from taking the difference between guesses, make it positive */ if (axRegister < 0) axRegister *= CONSTANT_NEG_1; //////////////////////////////////////////////////////////////////////// /* 16 - 23 We need to find out if the difference is 1. If it is, we can't half the difference because floats aren't supported and the difference will come out to 0. So if it's 1, we'll add 1, so that half of that is 1. So, we'll take 1 away from the value and check if it's still positive. If it is not, add 2 (one for the one we previously subtracted, and 1 for making the result of the division 1). If it is positive, add only 1 for the one we previously subtracted. */ axRegister -= 1; if (axRegister > 0); else axRegister += 1; axRegister += 1; //////////////////////////////////////////////////////////////////////// /* 24 - 27 We need to divide the difference by two in order to add or subtract it from the lastGuess and then store it in a temporary place. */ axRegister /= CONSTANT_2; tempStorage = axRegister; //////////////////////////////////////////////////////////////////////// /* 28 - 31, 77 - 88, 98 - 99 We need check once more if the difference is 1 in order to increment our errorCount so that we will only permit 14 errors before telling the user that he/she has made an error and output errorOutput. (The value is 14 because with an upper bound of 100,000,000 the errorCounter will increment 14 times from 13 - 0. This is the only way to reach 0 with this algorithm.) So, we subtract 1 from the axRegister value and test whether the value is now 0. If it is, we subtract 14 from the error counter and test whether it now equals 0 (in order to indirectly test whether it was equal to 14), if this test proves false, we add 15 (14 for what we previously subtracted, and 1 more to increment the errorCounter. Then we save the value in errorCounter */ axRegister -= 1; if (axRegister == 0) { axRegister = errorCounter; axRegister -= 14; if (axRegister == 0) { System.out.println(errorOutput); System.exit(1); } axRegister += 15; errorCounter = axRegister; } //////////////////////////////////////////////////////////////////////// /* 32 - 37 Output the currentGuess and take userInput to find out if 0, the guess was too low, 1, the guess was too high, or 999, the guess was right */ System.out.print(currentGuess + "\n? "); try { userInput = Integer.parseInt(br.readLine()); } catch (Exception e) { e.printStackTrace(); } axRegister = userInput; //////////////////////////////////////////////////////////////////////// /* 38-39, 45 - 52 If the value was 0, the guess was too low, so to increase it, we will add our currentGuess to our previously computed tempStorage value. */ if (axRegister == 0) { axRegister = tempStorage; axRegister += currentGuess; tempStorage = axRegister; } //////////////////////////////////////////////////////////////////////// /* 40 - 43, 53 - 64 If the value was 1, the guess was too high, and we'll need to subtract the difference from the last guess. If the axRegister is now negative, multiply by a -1 to make it positive. */ if (axRegister == 1) { axRegister = tempStorage; axRegister -= currentGuess; tempStorage = axRegister; if (axRegister > 0); else { axRegister *= CONSTANT_NEG_1; tempStorage = axRegister; } } //////////////////////////////////////////////////////////////////////// /* 44 If the userInput was not 0 and not 1, then we assume it is 999 and that we guessed correctly. We then terminate the program. */ else if (axRegister == 999) { System.exit(0); } //////////////////////////////////////////////////////////////////////// /* 65 - 72 Now we need to move the currentGuess to the lastGuess and our tempStorage value to the currentGuess for the next iteration. */ axRegister = currentGuess; lastGuess = axRegister; axRegister = tempStorage; currentGuess = axRegister; //////////////////////////////////////////////////////////////////////// /* 73 - 76 The axRegister value should never be negative at this stage, so whether it's positive or zero, continue the loop. */ if (axRegister > 0) continue; if (axRegister == 0) continue; //////////////////////////////////////////////////////////////////////// } } public static void main(String[] args) { NumberGuesser numberGuesser = new NumberGuesser(); } }