Solution to today's problem

Author: spannm

src/main/java/io/github/spannm/leetcode/lc0/lc0800/Problem0857.java

@@ -2,43 +2,41 @@
 
 import io.github.spannm.leetcode.LeetcodeProblem;
 
-import java.util.Arrays;
-import java.util.Comparator;
 import java.util.PriorityQueue;
+import java.util.Queue;
+import java.util.stream.IntStream;
 
 /**
  * 857. Minimum Cost to Hire K Workers.
  */
 class Problem0857 extends LeetcodeProblem {
 
     double mincostToHireWorkers(int[] _quality, int[] _wage, int _k) {
-        int n = _quality.length;
-        Pair[] t = new Pair[n];
-        for (int i = 0; i < n; i++) {
-            t[i] = new Pair(_quality[i], _wage[i]);
-        }
-        Arrays.sort(t, Comparator.comparingDouble(a -> a.x));
-        PriorityQueue<Integer> pq = new PriorityQueue<>((a, b) -> b - a);
-        double ans = 1e9;
+        Worker[] workers = IntStream.range(0, _quality.length)
+            .mapToObj(i -> new Worker(_quality[i], _wage[i]))
+            .sorted((_w1, _w2) -> Double.compare(_w1.wagePerQ, _w2.wagePerQ))
+            .toArray(Worker[]::new);
+        Queue<Integer> pq = new PriorityQueue<>((a, b) -> b - a);
+        double amt = 1e9;
         int tot = 0;
-        for (var e : t) {
-            tot += e.q;
-            pq.offer(e.q);
+        for (var w : workers) {
+            tot += w.quality;
+            pq.offer(w.quality);
             if (pq.size() == _k) {
-                ans = Math.min(ans, tot * e.x);
+                amt = Math.min(amt, tot * w.wagePerQ);
                 tot -= pq.poll();
             }
         }
-        return ans;
+        return amt;
     }
 
-    static class Pair {
-        private final double x;
-        private final int    q;
+    static class Worker {
+        private final int    quality;  // quality
+        private final double wagePerQ; // wage per quality
 
-        Pair(int _q, int _w) {
-            q = _q;
-            x = (double) _w / _q;
+        Worker(int _q, int _w) {
+            quality = _q;
+            wagePerQ = (double) _w / _q;
         }
 
     }

src/test/java/io/github/spannm/leetcode/lc0/lc0800/Problem0857Test.java

@@ -0,0 +1,23 @@
+package io.github.spannm.leetcode.lc0.lc0800;
+
+import io.github.spannm.leetcode.LeetcodeBaseTest;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.converter.ConvertWith;
+import org.junit.jupiter.params.provider.CsvSource;
+
+class Problem0857Test extends LeetcodeBaseTest {
+
+    @ParameterizedTest(name = "[{index}] {0}; {1}; {2} --> {3}")
+    @CsvSource(delimiter = ';', value = {
+        "10,20,5; 70,50,30,; 2; 105.00",
+        "3,1,10,10,1; 4,8,2,2,7; 3; 30.66667"
+    })
+    void test(
+        @ConvertWith(CsvToIntArray.class) int[] _quality,
+        @ConvertWith(CsvToIntArray.class) int[] _wage,
+        int _k,
+        double _expectedResult) {
+        assertEquals(_expectedResult, new Problem0857().mincostToHireWorkers(_quality, _wage, _k), 0.00001);
+    }
+
+}