implement tool

yangdanny97 · yangdanny97 · commit ab883c02d9af · 2023-01-31T13:55:25.000-08:00
diff --git a/index.html b/index.html
@@ -0,0 +1,24 @@
+<!DOCTYPE html>
+<meta charset="utf-8">
+
+<body>
+    <div>
+        <p>
+            A simple online tool for converting between decimal numbers and their <a
+                href="https://en.wikipedia.org/wiki/Fibonacci_coding">Fibonacci coding</a>.
+        </p>
+        <br>
+        <div>
+            Input:
+            <input type="text" id="input" size="50">
+            <button id="d2f">Decimal to Fibonacci</button>
+            <button id="f2d">Fibonacci to Decimal</button>
+        </div>
+        <br>
+        <div>
+            Output:
+            <input type="text" id="output" size="50">
+        </div>
+    </div>
+    <script src="./script.js"></script>
+</body>
diff --git a/script.js b/script.js
@@ -0,0 +1,55 @@
+const d2f = num => {
+    const helper = (f1, f2, n) => {
+        if (f2 > n) {
+            return [n, "1"];
+        }
+        [rem, b] = helper(f2, f1 + f2, n);
+        if (rem >= f2) {
+            return [rem - f2, "1" + b];
+        } else {
+            return [rem, "0" + b];
+        }
+    }
+    if (num <= 0) {
+        return "Number must be greater than 0";
+    }
+    return helper(1, 1, num)[1];
+};
+
+const f2d = b => {
+    const helper = (f1, f2, i) => {
+        if (i >= b.length - 1) {
+            return 0;
+        }
+        const char = b.charAt(i);
+        if (char == '1') {
+            return f2 + helper(f2, f1 + f2, i + 1);
+        } else if (char == '0') {
+            return helper(f2, f1 + f2, i + 1);
+        }
+    }
+    for (var i = 0; i < b.length; i++) {
+        switch (b.charAt(i)) {
+            case '1':
+            case '0':
+                break;
+            default:
+                return `Invalid character at position ${i}: ${b.charAt(i)}`;
+        }
+    }
+    if (b.length < 2 || b.charAt(b.length - 1) != '1' || b.charAt(b.length - 2) != '1') {
+        return "Last two bits must be 1";
+    }
+    return helper(1, 1, 0);
+};
+
+document.getElementById("d2f").addEventListener("click", () => {
+    const input = document.getElementById("input").value;
+    const output = d2f(parseInt(input));
+    document.getElementById("output").value = output;
+});
+document.getElementById("f2d").addEventListener("click", () => {
+    const input = document.getElementById("input").value;
+    const output = f2d(input);
+    document.getElementById("output").value = output.toString();
+});
