Data update

Task/Average-loop-length/JavaScript/average-loop-length.js

@@ -0,0 +1,49 @@
+const MAX_N = 20
+const TIMES = 1000000
+
+function factorial(n) {
+    let prod = 1;
+    for (let i = n; i > 1; i--) {
+        prod *= i;
+    }
+    return prod;
+}
+
+function getRandomInt(min, max) {
+  min = Math.ceil(min);
+  max = Math.floor(max);
+  return Math.floor(Math.random() * (max - min + 1)) + min;
+}
+
+
+function analytical(n) {
+    let items = [];
+
+    for (let i = 1; i < n+1; i++) {
+        items.push(factorial(n) / Math.pow(n, i) / factorial(n - i));
+    }
+
+    return items.reduce((p, v) => p + v, 0);
+}
+
+function test(n, times) {
+    let count = 0;
+    for (let i = 0; i < times; i++) {
+        let x = 1, bits = 0;
+
+        while (!(bits & x)) {
+            count += 1;
+            bits |= x;
+            x = 1 << getRandomInt(0, n-1);
+        }
+    }
+    return count / times;
+}
+
+console.log(" n\tavg\texp.\tdiff\n-------------------------------");
+for(let n = 1; n < MAX_N+1; n++) {
+    const avg = test(n, TIMES);
+    const theory = analytical(n);
+    const diff = (avg / theory - 1) * 100;
+    console.log(`${n.toString().padStart(2)} ${avg.toFixed(4).padStart(8)} ${theory.toFixed(4).padStart(8)} ${diff.toFixed(3).padStart(6)}%`);
+}