Data commit

Task/24-game/PHP/24-game.php

@@ -0,0 +1,94 @@
+#!/usr/bin/env php
+The 24 Game
+
+Given any four digits in the range 1 to 9, which may have repetitions,
+Using just the +, -, *, and / operators; and the possible use of
+brackets, (), show how to make an answer of 24.
+
+An answer of "q" will quit the game.
+An answer of "!" will generate a new set of four digits.
+Otherwise you are repeatedly asked for an expression until it evaluates to 24
+
+Note: you cannot form multiple digit numbers from the supplied digits,
+so an answer of 12+12 when given 1, 2, 2, and 1 would not be allowed.
+
+<?php
+
+while (true) {
+    $numbers = make_numbers();
+
+    for ($iteration_num = 1; ; $iteration_num++) {
+        echo "Expresion $iteration_num: ";
+
+        $entry = rtrim(fgets(STDIN));
+
+        if ($entry === '!') break;
+        if ($entry === 'q') exit;
+
+        $result = play($numbers, $entry);
+
+        if ($result === null) {
+            echo "That's not valid\n";
+            continue;
+        }
+        elseif ($result != 24) {
+            echo "Sorry, that's $result\n";
+            continue;
+        }
+        else {
+            echo "That's right! 24!!\n";
+            exit;
+        }
+    }
+}
+
+function make_numbers() {
+    $numbers = array();
+
+    echo "Your four digits: ";
+
+    for ($i = 0; $i < 4; $i++) {
+        $number = rand(1, 9);
+        // The check is needed to avoid E_NOTICE from PHP
+        if (!isset($numbers[$number])) {
+            $numbers[$number] = 0;
+        }
+        $numbers[$number]++;
+        print "$number ";
+    }
+
+    print "\n";
+
+    return $numbers;
+}
+
+function play($numbers, $expression) {
+    $operator = true;
+    for ($i = 0, $length = strlen($expression); $i < $length; $i++) {
+        $character = $expression[$i];
+
+        if (in_array($character, array('(', ')', ' ', "\t"))) continue;
+
+        $operator = !$operator;
+
+        if (!$operator) {
+            if (!empty($numbers[$character])) {
+                $numbers[$character]--;
+                continue;
+            }
+            return;
+        }
+        elseif (!in_array($character, array('+', '-', '*', '/'))) {
+            return;
+        }
+    }
+
+    foreach ($numbers as $remaining) {
+        if ($remaining > 0) {
+            return;
+        }
+    }
+
+    return eval("return $expression;");
+}
+?>