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linked-list.go
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194 lines (148 loc) · 2.86 KB
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package dsa
import (
"fmt"
"strconv"
"strings"
)
type Node struct {
Value int
Next *Node
}
// [LeetCode题](https://leetcode.cn/problems/design-linked-list)
type MyLinkedList struct {
Header *Node
// 增加 Tail 字段可以快速在链表尾部增加节点
Tail *Node
Len int
}
func Constructor() MyLinkedList {
return MyLinkedList{
Header: nil,
Tail: nil,
Len: 0,
}
}
// Get return the i'th node value, if index out range then return -1
func (ll *MyLinkedList) Get(i int) (value int) {
if i > ll.Len-1 || i < 0 {
return -1
}
return ll.getByIndex(i).Value
}
func (ll *MyLinkedList) AddAtHead(value int) {
node := newNode(value)
node.Next = ll.Header
ll.Header = node
if ll.Tail == nil {
ll.Tail = node
}
ll.Len++
}
func (ll *MyLinkedList) getByIndex(i int) *Node {
dummy := ll.Header
for index := 0; index < i; index++ {
dummy = dummy.Next
}
return dummy
}
// Insert the value node in index'th, if i greater then list'size, it do nothing
func (ll *MyLinkedList) Insert(index int, value int) {
switch {
case index > ll.Len:
return
case index == 0:
ll.AddAtHead(value)
return
case index == ll.Len:
ll.AddAtTail(value)
return
}
node := newNode(value)
preNode := ll.getByIndex(index - 1)
node.Next = preNode.Next
preNode.Next = node
ll.Len++
}
func (ll *MyLinkedList) AddAtTail(value int) {
node := newNode(value)
if ll.Len == 0 {
ll.Header = node
}
if ll.Tail != nil {
ll.Tail.Next = node
}
ll.Tail = node
ll.Len++
}
func (ll *MyLinkedList) AddAtIndex(index, value int) {
if index > ll.Len {
return
}
node := newNode(value)
if index <= 0 {
node.Next = ll.Header
ll.Header = node
// append of last
} else if index == ll.Len {
if ll.Tail != nil {
ll.Tail.Next = node
}
ll.Tail = node
} else {
// at middle
prev := ll.getByIndex(index - 1)
node.Next = prev.Next
prev.Next = node
fmt.Println(ll)
}
ll.Len++
}
func (ll *MyLinkedList) DeleteAtIndex(i int) {
if i >= ll.Len {
return
}
preNode := ll.getByIndex(i - 1)
if i == ll.Len-1 {
ll.Tail = preNode
preNode.Next = nil
} else if i == 0 {
ll.Header = ll.Header.Next
} else {
preNode.Next = preNode.Next.Next
}
ll.Len--
}
func (ll *MyLinkedList) RemoveByValue(value int) {
dummy := ll.Header
var preNode *Node
for index := 0; dummy != nil && index < ll.Len; index++ {
if dummy.Value != value {
continue
}
// remove the first element
if preNode == nil {
ll.Header = ll.Header.Next
} else if dummy.Next == nil {
ll.Tail = preNode
preNode.Next = nil
}
preNode = dummy
dummy = dummy.Next
ll.Len--
}
}
func (ll *MyLinkedList) String() string {
sb := strings.Builder{}
dummy := ll.Header
for dummy != nil {
sb.WriteString(strconv.Itoa(dummy.Value))
dummy = dummy.Next
}
return sb.String()
}
func newNode(value int) *Node {
return &Node{
Value: value,
Next: nil,
}
}