Merge pull request #843 from 0xff-dev/2487

Add solution and test-cases for problem 2487

Author: 6boris

leetcode/2401-2500/2487.Remove-Nodes-From-Linked-List/README.md

@@ -1,28 +1,32 @@
 # [2487.Remove Nodes From Linked List][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 the `head` of a linked list.
 
-**Example 1:**
+Remove every node which has a node with a greater value anywhere to the right side of it.
 
-```
-Input: a = "11", b = "1"
-Output: "100"
-```
+Return the `head` of the modified linked list.
 
-## 题意
-> ...
+**Example 1:**  
 
-## 题解
+![1](./drawio.png)
 
-### 思路1
-> ...
-Remove Nodes From Linked List
-```go
+```
+Input: head = [5,2,13,3,8]
+Output: [13,8]
+Explanation: The nodes that should be removed are 5, 2 and 3.
+- Node 13 is to the right of node 5.
+- Node 13 is to the right of node 2.
+- Node 8 is to the right of node 3.
 ```
 
+**Example 2:**
+
+```
+Input: head = [1,1,1,1]
+Output: [1,1,1,1]
+Explanation: Every node has value 1, so no nodes are removed.
+```
 
 ## 结语
 

leetcode/2401-2500/2487.Remove-Nodes-From-Linked-List/Solution.go

@@ -1,5 +1,21 @@
 package Solution
 
-func Solution(x bool) bool {
-	return x
+type ListNode struct {
+	Val  int
+	Next *ListNode
+}
+
+func Solution(head *ListNode) *ListNode {
+	stack := []*ListNode{head}
+	w := head.Next
+	for ; w != nil; w = w.Next {
+		for len(stack) > 0 && stack[len(stack)-1].Val < w.Val {
+			stack = stack[:len(stack)-1]
+		}
+		stack = append(stack, w)
+	}
+	for i := 1; i < len(stack); i++ {
+		stack[i-1].Next = stack[i]
+	}
+	return stack[0]
 }

leetcode/2401-2500/2487.Remove-Nodes-From-Linked-List/Solution_test.go

@@ -10,12 +10,41 @@ func TestSolution(t *testing.T) {
 	//	测试用例
 	cases := []struct {
 		name   string
-		inputs bool
-		expect bool
+		inputs *ListNode
+		expect *ListNode
 	}{
-		{"TestCase", true, true},
-		{"TestCase", true, true},
-		{"TestCase", false, false},
+		{"TestCase1", &ListNode{
+			Val: 5,
+			Next: &ListNode{
+				Val: 2,
+				Next: &ListNode{
+					Val: 13,
+					Next: &ListNode{
+						Val:  3,
+						Next: &ListNode{Val: 8},
+					},
+				},
+			},
+		}, &ListNode{Val: 13, Next: &ListNode{Val: 8}}},
+		{"TestCase2", &ListNode{
+			Val: 1,
+			Next: &ListNode{
+				Val: 1,
+				Next: &ListNode{
+					Val:  1,
+					Next: &ListNode{Val: 1},
+				},
+			},
+		}, &ListNode{
+			Val: 1,
+			Next: &ListNode{
+				Val: 1,
+				Next: &ListNode{
+					Val:  1,
+					Next: &ListNode{Val: 1},
+				},
+			},
+		}},
 	}
 
 	//	开始测试
@@ -30,10 +59,10 @@ 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() {
 }