Add solution and test-cases for problem 857

Author: 0xff-dev

leetcode/801-900/0857.Minimum-Cost-to-Hire-K-Workers/README.md

@@ -1,28 +1,30 @@
 # [857.Minimum Cost to Hire K Workers][title]
 
-> [!WARNING|style:flat]
-> This question is temporarily unanswered if you have good ideas. Welcome to [Create Pull Request PR](https://github.com/kylesliu/awesome-golang-algorithm)
-
 ## Description
+There are `n` workers. You are given two integer arrays `quality` and `wage` where `quality[i]` is the quality of the `ith` worker and `wage[i]` is the minimum wage expectation for the `ith` worker.
+
+We want to hire exactly `k` workers to form a **paid group**. To hire a group of `k` workers, we must pay them according to the following rules:
+
+1. Every worker in the paid group must be paid at least their minimum wage expectation.
+2. In the group, each worker's pay must be directly proportional to their quality. This means if a worker’s quality is double that of another worker in the group, then they must be paid twice as much as the other worker.
+
+Given the integer `k`, return the least amount of money needed to form a paid group satisfying the above conditions. Answers within `10^-5` of the actual answer will be accepted.
 
 **Example 1:**
 
 ```
-Input: a = "11", b = "1"
-Output: "100"
+Input: quality = [10,20,5], wage = [70,50,30], k = 2
+Output: 105.00000
+Explanation: We pay 70 to 0th worker and 35 to 2nd worker.
 ```
 
-## 题意
-> ...
+**Example 2:**
 
-## 题解
-
-### 思路1
-> ...
-Minimum Cost to Hire K Workers
-```go
 ```
-
+Input: quality = [3,1,10,10,1], wage = [4,8,2,2,7], k = 3
+Output: 30.66667
+Explanation: We pay 4 to 0th worker, 13.33333 to 2nd and 3rd workers separately.
+```
 
 ## 结语
 

leetcode/801-900/0857.Minimum-Cost-to-Hire-K-Workers/Solution.go

@@ -1,5 +1,69 @@
 package Solution
 
-func Solution(x bool) bool {
+import (
+	"container/heap"
+	"math"
+	"sort"
+)
+
+type Pair struct {
+	wageRatio float64
+	quality   int
+}
+
+type PairList []Pair
+
+func (p PairList) Len() int { return len(p) }
+func (p PairList) Less(i, j int) bool {
+	return p[i].wageRatio < p[j].wageRatio
+}
+func (p PairList) Swap(i, j int) {
+	p[i], p[j] = p[j], p[i]
+}
+
+type MaxHeap []int
+
+func (h MaxHeap) Len() int           { return len(h) }
+func (h MaxHeap) Less(i, j int) bool { return h[i] > h[j] }
+func (h MaxHeap) Swap(i, j int)      { h[i], h[j] = h[j], h[i] }
+func (h *MaxHeap) Push(x interface{}) {
+	*h = append(*h, x.(int))
+}
+func (h *MaxHeap) Pop() interface{} {
+	old := *h
+	n := len(old)
+	x := old[n-1]
+	*h = old[0 : n-1]
 	return x
 }
+
+func Solution(quality []int, wage []int, k int) float64 {
+	n := len(quality)
+	totalCost := float64(1<<63 - 1)
+	currentTotalQuality := 0.0
+	wageToQualityRatio := make(PairList, n)
+
+	for i := 0; i < n; i++ {
+		wageToQualityRatio[i] = Pair{float64(wage[i]) / float64(quality[i]), quality[i]}
+	}
+
+	sort.Sort(wageToQualityRatio)
+
+	highestQualityWorkers := &MaxHeap{}
+	heap.Init(highestQualityWorkers)
+
+	for i := 0; i < n; i++ {
+		heap.Push(highestQualityWorkers, wageToQualityRatio[i].quality)
+		currentTotalQuality += float64(wageToQualityRatio[i].quality)
+
+		if highestQualityWorkers.Len() > k {
+			currentTotalQuality -= float64(heap.Pop(highestQualityWorkers).(int))
+		}
+
+		if highestQualityWorkers.Len() == k {
+			totalCost = math.Min(totalCost, currentTotalQuality*wageToQualityRatio[i].wageRatio)
+		}
+	}
+
+	return totalCost
+}

leetcode/801-900/0857.Minimum-Cost-to-Hire-K-Workers/Solution_test.go

@@ -10,30 +10,30 @@ func TestSolution(t *testing.T) {
 	//	测试用例
 	cases := []struct {
 		name   string
-		inputs bool
-		expect bool
+		q, w   []int
+		k      int
+		expect float64
 	}{
-		{"TestCase", true, true},
-		{"TestCase", true, true},
-		{"TestCase", false, false},
+		{"TestCase1", []int{10, 20, 5}, []int{70, 50, 30}, 2, 105.0000},
+		{"TestCase2", []int{3, 1, 10, 10, 1}, []int{4, 8, 2, 2, 7}, 3, 30.666666666666664},
 	}
 
 	//	开始测试
 	for i, c := range cases {
 		t.Run(c.name+" "+strconv.Itoa(i), func(t *testing.T) {
-			got := Solution(c.inputs)
+			got := Solution(c.q, c.w, c.k)
 			if !reflect.DeepEqual(got, c.expect) {
-				t.Fatalf("expected: %v, but got: %v, with inputs: %v",
-					c.expect, got, c.inputs)
+				t.Fatalf("expected: %v, but got: %v, with inputs: %v %v %v",
+					c.expect, got, c.q, c.w, c.k)
 			}
 		})
 	}
 }
 
-//	压力测试
+// 压力测试
 func BenchmarkSolution(b *testing.B) {
 }
 
-//	使用案列
+// 使用案列
 func ExampleSolution() {
 }