Closest friends

closest-friends/index.js

@@ -0,0 +1,21 @@
+// https://www.codewars.com/kata/58791aa554a6783827000221/javascript
+
+const phoneMap = new Map();
+for (let name in phonebook) {
+  phoneMap.set(phonebook[name], name);
+}
+
+function closestFriends(history) {
+  const sum = new Map();
+  history.map(entry => {
+    const m = entry.match(/^(.*) (\d{2}):(\d{2}):(\d{2})$/);
+    const [PHONE, H, M, S] = [1, 2, 3, 4];
+    let duration = (+m[H]) * 3600 + (+m[M]) * 60 + (+m[S]);
+    if (sum.has(m[PHONE])) {
+      duration += +sum.get(m[PHONE]);
+    }
+    sum.set(m[PHONE], duration);
+  });
+  const top3 = [...sum].sort((a, b) => +b[1] - +a[1]).slice(0, 3);
+  return top3.map(e => phoneMap.get(e[0]));
+}