Merge pull request #1320 from 0xff-dev/1912

Add solution and test-cases for problem 1912

Author: 6boris

leetcode/1901-2000/1912.Design-Movie-Rental-System/README.md

@@ -1,28 +1,45 @@
 # [1912.Design Movie Rental System][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
+You have a movie renting company consisting of `n` shops. You want to implement a renting system that supports searching for, booking, and returning movies. The system should also support generating a report of the currently rented movies.
 
-**Example 1:**
+Each movie is given as a 2D integer array `entries` where `entries[i] = [shopi, moviei, pricei]` indicates that there is a copy of movie `moviei` at shop `shopi` with a rental price of `pricei`. Each shop carries **at most one** copy of a movie `moviei`.
 
-```
-Input: a = "11", b = "1"
-Output: "100"
-```
+The system should support the following functions:
 
-## 题意
-> ...
+- **Search**: Finds the **cheapest 5 shops** that have an **unrented copy** of a given movie. The shops should be sorted by **price** in ascending order, and in case of a tie, the one with the **smaller** `shopi` should appear first. If there are less than 5 matching shops, then all of them should be returned. If no shop has an unrented copy, then an empty list should be returned.
+- **Rent**: Rents an **unrented copy** of a given movie from a given shop.
+- **Drop**: Drops off a **previously rented copy** of a given movie at a given shop.
+- **Report**: Returns the **cheapest 5 rented movies** (possibly of the same movie ID) as a 2D list `res` where `res[j] = [shopj, moviej]` describes that the `jth` cheapest rented movie `moviei` was rented from the shop `shopj`. The movies in `res` should be sorted by **price** in ascending order, and in case of a tie, the one with the **smaller** shopj should appear first, and if there is still tie, the one with the **smaller** `moviej` should appear first. If there are fewer than 5 rented movies, then all of them should be returned. If no movies are currently being rented, then an empty list should be returned.
 
-## 题解
+Implement the `MovieRentingSystem` class:
 
-### 思路1
-> ...
-Design Movie Rental System
-```go
-```
+- `MovieRentingSystem(int n, int[][] entries)` Initializes the `MovieRentingSystem` object with `n` shops and the movies in `entries`.
+- `List<Integer> search(int movie)` Returns a list of shops that have an **unrented copy** of the given `movie` as described above.
+- `void rent(int shop, int movie)` Rents the given `movie` from the given `shop`.
+- `void drop(int shop, int movie)` Drops off a previously rented `movie` at the given `shop`.
+- `List<List<Integer>> report()` Returns a list of cheapest **rented** movies as described above.
 
+**Note**: The test cases will be generated such that `rent` will only be called if the shop has an **unrented** copy of the movie, and `drop` will only be called if the shop had **previously rented** out the movie.
+
+**Example 1:**
+
+```
+Input
+["MovieRentingSystem", "search", "rent", "rent", "report", "drop", "search"]
+[[3, [[0, 1, 5], [0, 2, 6], [0, 3, 7], [1, 1, 4], [1, 2, 7], [2, 1, 5]]], [1], [0, 1], [1, 2], [], [1, 2], [2]]
+Output
+[null, [1, 0, 2], null, null, [[0, 1], [1, 2]], null, [0, 1]]
+
+Explanation
+MovieRentingSystem movieRentingSystem = new MovieRentingSystem(3, [[0, 1, 5], [0, 2, 6], [0, 3, 7], [1, 1, 4], [1, 2, 7], [2, 1, 5]]);
+movieRentingSystem.search(1);  // return [1, 0, 2], Movies of ID 1 are unrented at shops 1, 0, and 2. Shop 1 is cheapest; shop 0 and 2 are the same price, so order by shop number.
+movieRentingSystem.rent(0, 1); // Rent movie 1 from shop 0. Unrented movies at shop 0 are now [2,3].
+movieRentingSystem.rent(1, 2); // Rent movie 2 from shop 1. Unrented movies at shop 1 are now [1].
+movieRentingSystem.report();   // return [[0, 1], [1, 2]]. Movie 1 from shop 0 is cheapest, followed by movie 2 from shop 1.
+movieRentingSystem.drop(1, 2); // Drop off movie 2 at shop 1. Unrented movies at shop 1 are now [1,2].
+movieRentingSystem.search(2);  // return [0, 1]. Movies of ID 2 are unrented at shops 0 and 1. Shop 0 is cheapest, followed by shop 1.
+```
 
 ## 结语
 

leetcode/1901-2000/1912.Design-Movie-Rental-System/Solution.go

@@ -1,5 +1,184 @@
 package Solution
 
-func Solution(x bool) bool {
+import (
+	"container/heap"
+	"sort"
+)
+
+type movie struct {
+	shop, movie, price, index int
+}
+
+type movieList []*movie
+
+func (m *movieList) Len() int {
+	return len(*m)
+}
+func (m *movieList) Swap(i, j int) {
+	(*m)[i], (*m)[j] = (*m)[j], (*m)[i]
+	(*m)[i].index = i
+	(*m)[j].index = j
+}
+
+func (m *movieList) Less(i, j int) bool {
+	a, b := (*m)[i], (*m)[j]
+	if a.price != b.price {
+		return a.price < b.price
+	}
+	if a.shop != b.shop {
+		return a.shop < b.shop
+	}
+	return a.movie < b.movie
+}
+
+func (m *movieList) Push(x any) {
+	mv := x.(*movie)
+	l := len(*m)
+	mv.index = l
+	*m = append(*m, mv)
+}
+
+func (m *movieList) Pop() any {
+	old := *m
+	l := len(old)
+	x := old[l-1]
+	*m = old[:l-1]
 	return x
 }
+
+type MovieRentingSystem struct {
+	// 每个电影自己的
+	movieShops map[int]*movieList
+	// 已经租界的电影列表
+	rentQueue *movieList
+	index     map[[2]int]*movie
+
+	n int
+}
+
+func Constructor(n int, entries [][]int) MovieRentingSystem {
+	instance := MovieRentingSystem{
+		movieShops: make(map[int]*movieList),
+		rentQueue:  &movieList{},
+		index:      make(map[[2]int]*movie),
+		n:          n,
+	}
+	// shop, movie, price
+	// movie, shop
+	for _, ent := range entries {
+		// shop, movie
+		key := [2]int{ent[0], ent[1]}
+		if _, ok := instance.movieShops[ent[1]]; !ok {
+			instance.movieShops[ent[1]] = &movieList{}
+		}
+		m := &movie{shop: ent[0], movie: ent[1], price: ent[2], index: 0}
+		instance.index[key] = m
+		heap.Push(instance.movieShops[ent[1]], m)
+	}
+	return instance
+}
+
+func (this *MovieRentingSystem) Search(m int) []int {
+	top5 := [][]int{}
+	list := this.movieShops[m]
+	if list == nil {
+		return nil
+	}
+	store := make([]*movie, 5)
+	index := 0
+	for list.Len() > 0 && index < 5 {
+		top := heap.Pop(list).(*movie)
+		store[index] = top
+		index++
+		top5 = append(top5, []int{top.shop, top.price})
+	}
+	for i := 0; i < index; i++ {
+		heap.Push(list, store[i])
+	}
+	sort.Slice(top5, func(i, j int) bool {
+		a, b := top5[i], top5[j]
+		if a[1] != b[1] {
+			return a[1] < b[1]
+		}
+		return a[0] < b[0]
+	})
+	ret := make([]int, len(top5))
+	for i := range top5 {
+		ret[i] = top5[i][0]
+	}
+
+	return ret
+}
+
+func (this *MovieRentingSystem) Rent(shop int, m int) {
+	// 需要记录价格
+	key := [2]int{shop, m}
+	item := this.index[key]
+	_ = heap.Remove(this.movieShops[m], item.index)
+	heap.Push(this.rentQueue, item)
+}
+
+func (this *MovieRentingSystem) Drop(shop int, m int) {
+	key := [2]int{shop, m}
+	item := this.index[key]
+	heap.Remove(this.rentQueue, item.index)
+	heap.Push(this.movieShops[m], item)
+}
+
+func (this *MovieRentingSystem) Report() [][]int {
+	top5 := [][]int{}
+	store := make([]*movie, 5)
+	index := 0
+	for this.rentQueue.Len() > 0 && index < 5 {
+		top := heap.Pop(this.rentQueue).(*movie)
+		store[index] = top
+		index++
+		top5 = append(top5, []int{top.shop, top.movie, top.price})
+	}
+	for i := 0; i < index; i++ {
+		heap.Push(this.rentQueue, store[i])
+	}
+
+	sort.Slice(top5, func(i, j int) bool {
+		a, b := top5[i], top5[j]
+		if a[2] != b[2] {
+			return a[2] < b[2]
+		}
+		if a[0] != b[0] {
+			return a[0] < b[0]
+		}
+		return a[1] < b[1]
+	})
+	ret := make([][]int, len(top5))
+	for i := range top5 {
+		ret[i] = top5[i][:2]
+	}
+
+	return ret
+}
+
+type op struct {
+	name        string
+	shop, movie int
+}
+
+func Solution(m int, entries [][]int, ops []op) []any {
+	c := Constructor(m, entries)
+	ret := make([]any, 0)
+	for _, o := range ops {
+		if o.name == "rent" {
+			c.Rent(o.shop, o.movie)
+			continue
+		}
+		if o.name == "drop" {
+			c.Drop(o.shop, o.movie)
+			continue
+		}
+		if o.name == "search" {
+			ret = append(ret, c.Search(o.movie))
+			continue
+		}
+		ret = append(ret, c.Report())
+	}
+	return ret
+}

leetcode/1901-2000/1912.Design-Movie-Rental-System/Solution_test.go

@@ -9,31 +9,40 @@ import (
 func TestSolution(t *testing.T) {
 	//	测试用例
 	cases := []struct {
-		name   string
-		inputs bool
-		expect bool
+		name    string
+		m       int
+		entries [][]int
+		ops     []op
+		expect  []any
 	}{
-		{"TestCase", true, true},
-		{"TestCase", true, true},
-		{"TestCase", false, false},
+		{"TestCase1", 3, [][]int{
+			{0, 1, 5}, {0, 2, 6}, {0, 3, 7}, {1, 1, 4}, {1, 2, 7}, {2, 1, 5},
+		}, []op{
+			{name: "search", movie: 1},
+			{name: "rent", shop: 0, movie: 1},
+			{name: "rent", shop: 1, movie: 2},
+			{name: "report"},
+			{name: "drop", shop: 1, movie: 2},
+			{name: "search", movie: 2},
+		}, []any{[]int{1, 0, 2}, [][]int{{0, 1}, {1, 2}}, []int{0, 1}}},
 	}
 
 	//	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.m, c.entries, c.ops)
 			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.m, c.entries, c.ops)
 			}
 		})
 	}
 }
 
-//	压力测试
+// 压力测试
 func BenchmarkSolution(b *testing.B) {
 }
 
-//	使用案列
+// 使用案列
 func ExampleSolution() {
 }