95 lines
2.2 KiB
PHP
95 lines
2.2 KiB
PHP
#!/usr/bin/env php
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The 24 Game
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Given any four digits in the range 1 to 9, which may have repetitions,
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Using just the +, -, *, and / operators; and the possible use of
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brackets, (), show how to make an answer of 24.
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An answer of "q" will quit the game.
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An answer of "!" will generate a new set of four digits.
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Otherwise you are repeatedly asked for an expression until it evaluates to 24
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Note: you cannot form multiple digit numbers from the supplied digits,
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so an answer of 12+12 when given 1, 2, 2, and 1 would not be allowed.
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<?php
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while (true) {
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$numbers = make_numbers();
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for ($iteration_num = 1; ; $iteration_num++) {
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echo "Expresion $iteration_num: ";
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$entry = rtrim(fgets(STDIN));
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if ($entry === '!') break;
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if ($entry === 'q') exit;
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$result = play($numbers, $entry);
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if ($result === null) {
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echo "That's not valid\n";
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continue;
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}
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elseif ($result != 24) {
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echo "Sorry, that's $result\n";
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continue;
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}
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else {
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echo "That's right! 24!!\n";
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exit;
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}
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}
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}
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function make_numbers() {
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$numbers = array();
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echo "Your four digits: ";
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for ($i = 0; $i < 4; $i++) {
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$number = rand(1, 9);
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// The check is needed to avoid E_NOTICE from PHP
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if (!isset($numbers[$number])) {
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$numbers[$number] = 0;
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}
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$numbers[$number]++;
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print "$number ";
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}
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print "\n";
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return $numbers;
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}
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function play($numbers, $expression) {
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$operator = true;
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for ($i = 0, $length = strlen($expression); $i < $length; $i++) {
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$character = $expression[$i];
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if (in_array($character, array('(', ')', ' ', "\t"))) continue;
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$operator = !$operator;
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if (!$operator) {
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if (!empty($numbers[$character])) {
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$numbers[$character]--;
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continue;
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}
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return;
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}
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elseif (!in_array($character, array('+', '-', '*', '/'))) {
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return;
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}
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}
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foreach ($numbers as $remaining) {
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if ($remaining > 0) {
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return;
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}
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}
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return eval("return $expression;");
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}
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?>
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