reorg and add code for second edition

10_greedy_algorithms/ES6/01_set_covering.js

@@ -0,0 +1,28 @@
+// You pass an array in, and it gets converted to a set.
+let statesNeeded = 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 finalStations = new Set();
+
+while (statesNeeded.size) {
+  let bestStation = null;
+  let statesCovered = new Set();
+  Object.keys(stations).forEach(station => {
+    const states = stations[station];
+    const covered = new Set([...statesNeeded].filter(x => states.has(x)));
+    if (covered.size > statesCovered.size) {
+      bestStation = station;
+      statesCovered = covered;
+    }
+  });
+  statesNeeded = new Set([...statesNeeded].filter(x => !statesCovered.has(x)));
+  finalStations.add(bestStation);
+}
+
+console.log(finalStations); // Set { 'kone', 'ktwo', 'kthree', 'kfive' }