code for chapter 8 in javascript

08_greedy_algorithms/javascript/01_set_covering.js

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+'use strict';
+
+// You pass an array in, and it gets converted to a set.
+let states_needed = new Set(["mt", "wa", "or", "id", "nv", "ut", "ca", "az"]);
+
+const stations = {};
+stations["kone"] = new Set(["id", "nv", "ut"]);
+stations["ktwo"] = new Set(["wa", "id", "mt"]);
+stations["kthree"] = new Set(["or", "nv", "ca"]);
+stations["kfour"] = new Set(["nv", "ut"]);
+stations["kfive"] = new Set(["ca", "az"]);
+
+const final_stations = new Set();
+
+
+while (states_needed.size) {
+  let best_station = null;
+  let states_covered = new Set();
+  for (let station in stations) {
+    let states = stations[station];
+    let covered = new Set([...states_needed].filter((x) => states.has(x)));
+    if (covered.size > states_covered.size) {
+      best_station = station;
+      states_covered = covered;
+    }
+  }
+  states_needed = new Set([...states_needed].filter((x) => !states_covered.has(x)));
+  final_stations.add(best_station);
+}
+
+console.log(final_stations); // Set { 'kone', 'ktwo', 'kthree', 'kfive' }