Merge pull request #370 from 0xff-dev/1026

Add solution and test-cases for problem 1026

Author: Cori1109

leetcode/1001-1100/1026.Maximum-Difference-Between-Node-and-Ancestor/README.md

@@ -1,28 +1,31 @@
 # [1026.Maximum Difference Between Node and Ancestor][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
+Given the `root` of a binary tree, find the maximum value `v` for which there exist **different** nodes `a` and `b` where `v = |a.val - b.val|` and `a` is an ancestor of `b`.
+
+A node `a` is an ancestor of `b` if either: any child of `a` is equal to `b` any child of `a` is an ancestor of `b`.
 
-**Example 1:**
+**Example 1:**  
+![example1](./tmp-tree.jpg)
 
 ```
-Input: a = "11", b = "1"
-Output: "100"
+Input: root = [8,3,10,1,6,null,14,null,null,4,7,13]
+Output: 7
+Explanation: We have various ancestor-node differences, some of which are given below :
+|8 - 3| = 5
+|3 - 7| = 4
+|8 - 1| = 7
+|10 - 13| = 3
+Among all possible differences, the maximum value of 7 is obtained by |8 - 1| = 7.
 ```
 
-## 题意
-> ...
-
-## 题解
+**Example 2:**  
+![example2](./tmp-tree-1.jpg)  
 
-### 思路1
-> ...
-Maximum Difference Between Node and Ancestor
-```go
 ```
-
+Input: root = [1,null,2,null,0,3]
+Output: 3
+```
 
 ## 结语
 

leetcode/1001-1100/1026.Maximum-Difference-Between-Node-and-Ancestor/Solution.go

@@ -1,5 +1,50 @@
 package Solution
 
-func Solution(x bool) bool {
-	return x
+type TreeNode struct {
+	Val         int
+	Left, Right *TreeNode
+}
+
+func Solution(root *TreeNode) int {
+	if root == nil {
+		return 0
+	}
+	ans := -1
+	maxAncestorDiff1026(root, &ans)
+	return ans
+}
+
+func check1026(ans *int, others []int) (int, int) {
+	root, m, n := others[0], others[0], others[0]
+	for idx := 1; idx < len(others); idx++ {
+		diff := others[idx] - root
+		if diff < 0 {
+			diff = -diff
+		}
+		if *ans == -1 || diff > *ans {
+			*ans = diff
+		}
+		if others[idx] > m {
+			m = others[idx]
+		}
+		if others[idx] < n {
+			n = others[idx]
+		}
+	}
+	return m, n
+}
+func maxAncestorDiff1026(root *TreeNode, ans *int) (int, int) {
+	other := []int{root.Val}
+	if root.Left != nil {
+
+		leftMax, leftMin := maxAncestorDiff1026(root.Left, ans)
+		other = append(other, leftMax, leftMin)
+	}
+
+	if root.Right != nil {
+		rightMax, rightMin := maxAncestorDiff1026(root.Right, ans)
+		other = append(other, rightMax, rightMin)
+	}
+
+	return check1026(ans, other)
 }

leetcode/1001-1100/1026.Maximum-Difference-Between-Node-and-Ancestor/Solution_test.go

@@ -10,12 +10,57 @@ func TestSolution(t *testing.T) {
 	//	测试用例
 	cases := []struct {
 		name   string
-		inputs bool
-		expect bool
+		inputs *TreeNode
+		expect int
 	}{
-		{"TestCase", true, true},
-		{"TestCase", true, true},
-		{"TestCase", false, false},
+		{"TestCase1", &TreeNode{
+			Val: 8,
+			Left: &TreeNode{
+				Val:  3,
+				Left: &TreeNode{Val: 1},
+				Right: &TreeNode{
+					Val:   6,
+					Left:  &TreeNode{Val: 4},
+					Right: &TreeNode{Val: 7},
+				},
+			},
+			Right: &TreeNode{
+				Val: 10,
+				Right: &TreeNode{
+					Val: 14,
+					Left: &TreeNode{
+						Val: 13,
+					},
+				},
+			},
+		}, 7},
+		{"TestCase2", &TreeNode{
+			Val: 1,
+			Right: &TreeNode{
+				Val: 2,
+				Right: &TreeNode{
+					Val: 0,
+					Left: &TreeNode{
+						Val: 3,
+					},
+				},
+			},
+		}, 3},
+		{"TestCase3", &TreeNode{
+			Val: 2,
+			Right: &TreeNode{
+				Val: 0,
+				Right: &TreeNode{
+					Val: 4,
+					Right: &TreeNode{
+						Val: 3,
+						Right: &TreeNode{
+							Val: 1,
+						},
+					},
+				},
+			},
+		}, 4},
 	}
 
 	//	开始测试
@@ -30,10 +75,10 @@ func TestSolution(t *testing.T) {
 	}
 }
 
-//	压力测试
+// 压力测试
 func BenchmarkSolution(b *testing.B) {
 }
 
-//	使用案列
+// 使用案列
 func ExampleSolution() {
 }