Merge pull request #917 from 0xff-dev/1993

Add solution and test-cases for problem 1993

Author: 6boris

leetcode/1901-2000/1993.Operations-on-Tree/README.md

@@ -1,28 +1,49 @@
 # [1993.Operations on Tree][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 are given a tree with `n` nodes numbered from `0` to `n - 1` in the form of a parent array `parent` where `parent[i]` is the parent of the i<sup>th</sup> node. The root of the tree is node `0`, so `parent[0] = -1` since it has no parent. You want to design a data structure that allows users to lock, unlock, and upgrade nodes in the tree.
 
-**Example 1:**
+The data structure should support the following functions:
 
-```
-Input: a = "11", b = "1"
-Output: "100"
-```
+- **Lock: Locks** the given node for the given user and prevents other users from locking the same node. You may only lock a node using this function if the node is unlocked.
+- **Unlock: Unlocks** the given node for the given user. You may only unlock a node using this function if it is currently locked by the same user.
+- **Upgrade: Locks** the given node for the given user and **unlocks** all of its descendants **regardless** of who locked it. You may only upgrade a node if **all** 3 conditions are true:
 
-## 题意
-> ...
+    - The node is unlocked,
+    - It has at least one locked descendant (by any user), and
+    - It does not have any locked ancestors.
 
-## 题解
+Implement the `LockingTree` class:
 
-### 思路1
-> ...
-Operations on Tree
-```go
-```
+- `LockingTree(int[] parent)` initializes the data structure with the parent array.
+- `lock(int num, int user)` returns `true` if it is possible for the `user` with id user to lock the node `num`, or false otherwise. If it is possible, the node `num` will become **locked** by the user with id `user`.
+- `unlock(int num, int user)` returns `true` if it is possible for the `user` with id user to unlock the node `num`, or `false` otherwise. If it is possible, the node `num` will become **unlocked**.
+- `upgrade(int num, int user)` returns `true` if it is possible for the `user` with id user to upgrade the node `num`, or `false` otherwise. If it is possible, the node `num` will be **upgraded**.
 
+**Example 1:**  
+
+![1](./untitled.png)
+
+```
+Input
+["LockingTree", "lock", "unlock", "unlock", "lock", "upgrade", "lock"]
+[[[-1, 0, 0, 1, 1, 2, 2]], [2, 2], [2, 3], [2, 2], [4, 5], [0, 1], [0, 1]]
+Output
+[null, true, false, true, true, true, false]
+
+Explanation
+LockingTree lockingTree = new LockingTree([-1, 0, 0, 1, 1, 2, 2]);
+lockingTree.lock(2, 2);    // return true because node 2 is unlocked.
+                           // Node 2 will now be locked by user 2.
+lockingTree.unlock(2, 3);  // return false because user 3 cannot unlock a node locked by user 2.
+lockingTree.unlock(2, 2);  // return true because node 2 was previously locked by user 2.
+                           // Node 2 will now be unlocked.
+lockingTree.lock(4, 5);    // return true because node 4 is unlocked.
+                           // Node 4 will now be locked by user 5.
+lockingTree.upgrade(0, 1); // return true because node 0 is unlocked and has at least one locked descendant (node 4).
+                           // Node 0 will now be locked by user 1 and node 4 will now be unlocked.
+lockingTree.lock(0, 1);    // return false because node 0 is already locked.
+```
 
 ## 结语
 

leetcode/1901-2000/1993.Operations-on-Tree/Solution.go

@@ -1,5 +1,102 @@
 package Solution
 
-func Solution(x bool) bool {
-	return x
+type LockingTree struct {
+	tree     []int
+	locker   []int
+	children map[int][]int
+}
+
+func Constructor(parent []int) LockingTree {
+	children := make(map[int][]int)
+	for c, p := range parent {
+		if _, ok := children[p]; !ok {
+			children[p] = make([]int, 0)
+		}
+		children[p] = append(children[p], c)
+	}
+	return LockingTree{tree: parent, locker: make([]int, len(parent)), children: children}
+}
+
+// u, u, ul, l, u
+func (this *LockingTree) Lock(num int, user int) bool {
+	if this.locker[num] != 0 {
+		return false
+	}
+	this.locker[num] = user
+	return true
+}
+
+func (this *LockingTree) Unlock(num int, user int) bool {
+	if this.locker[num] == 0 || this.locker[num] != user {
+		return false
+	}
+	this.locker[num] = 0
+	return true
+}
+
+func (this *LockingTree) ancesors(num int) bool {
+	for {
+		if num == -1 {
+			return false
+		}
+		if this.locker[num] != 0 {
+			return true
+		}
+		num = this.tree[num]
+	}
+}
+
+func (this *LockingTree) unlockDescendant(num int) bool {
+	q := []int{num}
+	found := false
+	for len(q) > 0 {
+		nq := make([]int, 0)
+		for _, i := range q {
+			if this.locker[i] != 0 {
+				this.locker[i] = 0
+				found = true
+			}
+			for _, c := range this.children[i] {
+				nq = append(nq, c)
+			}
+		}
+		q = nq
+	}
+	return found
+}
+
+func (this *LockingTree) Upgrade(num int, user int) bool {
+	if this.locker[num] != 0 {
+		return false
+	}
+	if this.ancesors(num) {
+		return false
+	}
+	if !this.unlockDescendant(num) {
+		return false
+	}
+	this.locker[num] = user
+	return true
+}
+
+type op struct {
+	name string
+	a, b int
+}
+
+func Solution(p []int, opts []op) []bool {
+	c := Constructor(p)
+	ans := make([]bool, 0)
+	for _, o := range opts {
+		if o.name == "l" {
+			ans = append(ans, c.Lock(o.a, o.b))
+			continue
+		}
+		if o.name == "u" {
+			ans = append(ans, c.Unlock(o.a, o.b))
+			continue
+		}
+		ans = append(ans, c.Upgrade(o.a, o.b))
+	}
+	return ans
 }

leetcode/1901-2000/1993.Operations-on-Tree/Solution_test.go

@@ -10,30 +10,36 @@ func TestSolution(t *testing.T) {
 	//	测试用例
 	cases := []struct {
 		name   string
-		inputs bool
-		expect bool
+		p      []int
+		opts   []op
+		expect []bool
 	}{
-		{"TestCase", true, true},
-		{"TestCase", true, true},
-		{"TestCase", false, false},
+		{"TestCase1", []int{-1, 0, 0, 1, 1, 2, 2}, []op{
+			{"l", 2, 2},
+			{"u", 2, 3},
+			{"u", 2, 2},
+			{"l", 4, 5},
+			{"", 0, 1},
+			{"l", 0, 1},
+		}, []bool{true, false, true, true, true, false}},
 	}
 
 	//	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.p, c.opts)
 			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",
+					c.expect, got, c.p, c.opts)
 			}
 		})
 	}
 }
 
-//	压力测试
+// 压力测试
 func BenchmarkSolution(b *testing.B) {
 }
 
-//	使用案列
+// 使用案列
 func ExampleSolution() {
 }