Family Day update

Task/Move-to-front-algorithm/PHP/move-to-front-algorithm.php

@@ -0,0 +1,44 @@
+<?php
+
+function symbolTable() {
+    $symbol = array();
+    for ($c = ord('a') ; $c <= ord('z') ; $c++) {
+        $symbol[$c - ord('a')] = chr($c);
+    }
+    return $symbol;
+}
+
+function mtfEncode($original, $symbol) {
+    $encoded = array();
+    for ($i = 0 ; $i < strlen($original) ; $i++) {
+        $char = $original[$i];
+        $position = array_search($char, $symbol);
+        $encoded[] = $position;
+        $mtf = $symbol[$position];
+        unset($symbol[$position]);
+        array_unshift($symbol, $mtf);
+    }
+    return $encoded;
+}
+
+function mtfDecode($encoded, $symbol) {
+    $decoded = '';
+    foreach ($encoded AS $position) {
+        $char = $symbol[$position];
+        $decoded .= $char;
+        unset($symbol[$position]);
+        array_unshift($symbol, $char);
+    }
+    return $decoded;
+}
+
+foreach (array('broood', 'bananaaa', 'hiphophiphop') AS $original) {
+    $encoded = mtfEncode($original, symbolTable());
+    $decoded = mtfDecode($encoded, symbolTable());
+    echo
+        $original,
+        ' -> [', implode(',', $encoded), ']',
+        ' -> ', $decoded,
+        ' : ', ($original === $decoded ? 'OK' : 'Error'),
+        PHP_EOL;
+}