Merge pull request #1237 from 0xff-dev/3319

Add solution and test-cases for problem 3319

Author: 6boris

leetcode/3301-3400/3319.K-th-Largest-Perfect-Subtree-Size-in-Binary-Tree/1.png

@@ -1,28 +1,55 @@
 # [3319.K-th Largest Perfect Subtree Size in Binary 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
 
-**Example 1:**
+You are given the `root` of a **binary tree** and an integer `k`.
+
+Return an integer denoting the size of the `kth` **largest perfect binary subtree**, or `-1` if it doesn't exist.
+
+A **perfect binary tree** is a tree where all leaves are on the same level, and every parent has two children.
+
+**Example 1:**  
+
+![1](./1.png)
 
 ```
-Input: a = "11", b = "1"
-Output: "100"
+Input: root = [5,3,6,5,2,5,7,1,8,null,null,6,8], k = 2
+
+Output: 3
+
+Explanation:
+
+The roots of the perfect binary subtrees are highlighted in black. Their sizes, in non-increasing order are [3, 3, 1, 1, 1, 1, 1, 1].
+The 2nd largest size is 3.
 ```
 
-## 题意
-> ...
+**Example 2:**  
 
-## 题解
+![2](./2.png)
 
-### 思路1
-> ...
-K-th Largest Perfect Subtree Size in Binary Tree
-```go
 ```
+Input: root = [1,2,3,4,5,6,7], k = 1
+
+Output: 7
+
+Explanation:
 
+The sizes of the perfect binary subtrees in non-increasing order are [7, 3, 3, 1, 1, 1, 1]. The size of the largest perfect binary subtree is 7.
+```
+
+**Example 3:**  
+
+![3](./3.png)
+
+```
+Input: root = [1,2,3,null,4], k = 3
+
+Output: -1
+
+Explanation:
+
+The sizes of the perfect binary subtrees in non-increasing order are [1, 1]. There are fewer than 3 perfect binary subtrees.
+```
 
 ## 结语
 

leetcode/3301-3400/3319.K-th-Largest-Perfect-Subtree-Size-in-Binary-Tree/2.png

@@ -1,5 +1,50 @@
 package Solution
 
-func Solution(x bool) bool {
-	return x
+import "sort"
+
+type TreeNode struct {
+	Val   int
+	Left  *TreeNode
+	Right *TreeNode
+}
+
+func Solution(root *TreeNode, k int) int {
+	var dfs func(*TreeNode) int
+	count := make(map[int]int)
+	dfs = func(cur *TreeNode) int {
+		if cur == nil {
+			return -1
+		}
+		if cur.Left == nil && cur.Right == nil {
+			count[1]++
+			// leaf
+			return 1
+		}
+		left := dfs(cur.Left)
+		right := dfs(cur.Right)
+
+		if left != -1 && left == right {
+			count[left+right+1]++
+			return left + right + 1
+		}
+		return -1
+	}
+	dfs(root)
+	keys := make([]int, 0)
+	for i := range count {
+		keys = append(keys, i)
+	}
+
+	sort.Slice(keys, func(i, j int) bool {
+		return keys[i] > keys[j]
+	})
+	var cnt int
+	for _, n := range keys {
+		cnt = count[n]
+		if cnt >= k {
+			return n
+		}
+		k -= cnt
+	}
+	return -1
 }

leetcode/3301-3400/3319.K-th-Largest-Perfect-Subtree-Size-in-Binary-Tree/3.png

@@ -10,30 +10,70 @@ func TestSolution(t *testing.T) {
 	//	测试用例
 	cases := []struct {
 		name   string
-		inputs bool
-		expect bool
+		inputs *TreeNode
+		k      int
+		expect int
 	}{
-		{"TestCase", true, true},
-		{"TestCase", true, true},
-		{"TestCase", false, false},
+		{"TestCase1", &TreeNode{
+			Val: 5,
+			Left: &TreeNode{
+				Val: 3,
+				Left: &TreeNode{
+					Val:   5,
+					Left:  &TreeNode{Val: 1},
+					Right: &TreeNode{Val: 8},
+				},
+				Right: &TreeNode{Val: 2},
+			},
+			Right: &TreeNode{
+				Val: 6,
+				Left: &TreeNode{
+					Val:   5,
+					Left:  &TreeNode{Val: 6},
+					Right: &TreeNode{Val: 8},
+				},
+				Right: &TreeNode{Val: 7},
+			},
+		}, 2, 3},
+		{"TestCase1", &TreeNode{
+			Val: 1,
+			Left: &TreeNode{
+				Val:   2,
+				Left:  &TreeNode{Val: 4},
+				Right: &TreeNode{Val: 5},
+			},
+			Right: &TreeNode{
+				Val:   3,
+				Left:  &TreeNode{Val: 6},
+				Right: &TreeNode{Val: 7},
+			},
+		}, 1, 7},
+		{"TestCase3", &TreeNode{
+			Val: 1,
+			Left: &TreeNode{
+				Val:   2,
+				Right: &TreeNode{Val: 4},
+			},
+			Right: &TreeNode{Val: 3},
+		}, 3, -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.inputs, 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",
+					c.expect, got, c.inputs, 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() {
 }