RogerBW solutions for challenge no. 211

1 files changed, 69 insertions, 0 deletions

diff --git a/challenge-211/roger-bell-west/javascript/ch-2.js b/challenge-211/roger-bell-west/javascript/ch-2.js
new file mode 100755
index 0000000000..75870a79b1
--- /dev/null
+++ b/challenge-211/roger-bell-west/javascript/ch-2.js
@@ -0,0 +1,69 @@
+#! /usr/bin/node
+
+"use strict"
+
+function combinations(arr, k) {
+    let c = [];
+    for (let i = 0; i < k; i++) {
+        c.push(i);
+    }
+    c.push(arr.length);
+    c.push(0);
+    let out = [];
+    while (true) {
+        let inner = [];
+        for (let i = k-1; i >= 0; i--) {
+            inner.push(arr[c[i]]);
+        }
+        out.push(inner);
+        let j = 0;
+        while (c[j] + 1 == c[j + 1]) {
+            c[j] = j;
+            j += 1;
+        }
+        if (j >= k) {
+            break;
+        }
+        c[j] += 1;
+    }
+    return out;
+}
+
+function splitsameaverage(a) {
+    let ss = a.reduce((x, y) => x + y, 0);
+    let ml = a.length;
+    let mx = Math.floor(ml / 2);
+    let ssa = false;
+    for (let n = 1; n <= mx; n++) {
+        for (let c of combinations(a, n)) {
+            let ca = c.reduce((x, y) => x + y, 0);
+            if (ca / n == (ss - ca) / (ml - n)) {
+                ssa = true;
+                break;
+            }
+        }
+        if (ssa) {
+            break;
+        }
+    }
+    return ssa;
+}
+
+if (splitsameaverage([1, 2, 3, 4, 5, 6, 7, 8])) {
+  process.stdout.write("Pass");
+} else {
+  process.stdout.write("FAIL");
+}
+process.stdout.write(" ");
+if (!splitsameaverage([1, 3])) {
+  process.stdout.write("Pass");
+} else {
+  process.stdout.write("FAIL");
+}
+process.stdout.write(" ");
+if (splitsameaverage([1, 2, 3])) {
+  process.stdout.write("Pass");
+} else {
+  process.stdout.write("FAIL");
+}
+process.stdout.write("\n");