public void deleteNode(ListNode head, int i) { if (i == 0 || head == null) { return; } if (i == 1) { head = head.next; return; } ListNode prev = head; for (int j = 1; j < i - 1 && prev != null && prev.next != null; j++) { prev = prev.next; } if (prev == null || prev.next == null) { return; } prev.next = prev.next.next;}
时间: 2024-01-04 08:02:03 浏览: 23
这是一个删除单链表中指定位置节点的函数。函数的参数包括链表头节点head和需要删除的节点位置i。具体实现如下:
1. 如果i为0或者head为null,则直接返回。
2. 如果i为1,则将head指向下一个节点即可,然后返回。
3. 如果i大于1,则需要遍历链表找到要删除节点的前一个节点prev。遍历过程中需要判断prev和prev.next是否为空,避免出现空指针异常。
4. 如果prev或者prev.next为空,则说明要删除的节点不存在,直接返回。
5. 如果找到了要删除的节点的前一个节点prev,则将prev.next指向要删除节点的下一个节点即可完成删除操作。
需要注意的是,由于Java是按值传递的,所以在第2步中修改head并不会影响函数外部的head值。如果要修改函数外部的head值,可以将head声明为ListNode[]类型,并传入长度为1的数组。在函数内部修改head[0]的值即可。
相关问题
#include<iostream> using namespace std; struct LinkedList { // todo: some variables here void initialize() { int n; scanf("%d", &n); int *a = new int[n]; for(int i = 0; i < n; i++) scanf("%d", &a[i]); // todo delete[] a; } void insert(int i, int x) { // todo } void erase(int i) { // todo } void swap() { // todo } void moveback(int i, int x) { // todo } int query(int i) { // todo } void printAll() { // todo } void ClearMemory() { // todo } }; int main() { LinkedList List; int m, op, i, x; List.initialize(); scanf("%d", &m); while(m--) { scanf("%d", &op); if(op == 1) { scanf("%d%d", &i, &x); List.insert(i, x); } else if(op == 2) { scanf("%d", &i); List.erase(i); } else if(op == 3) { List.swap(); } else if(op == 4) { scanf("%d%d",&i, &x); List.moveback(i, x); } else if(op == 5) { scanf("%d", &i); printf("%d\n", List.query(i)); } else if(op == 6) { List.printAll(); } } List.ClearMemory(); return 0; }
抱歉,上述代码并没有实现您的要求,只是一个模版代码。以下是根据您的要求修改后的代码实现单链表:
```c++
#include<iostream>
using namespace std;
struct ListNode {
int val;
ListNode *next;
ListNode(int x) : val(x), next(NULL) {}
};
class LinkedList {
private:
ListNode *head, *tail;
int size;
public:
LinkedList(): head(NULL), tail(NULL), size(0) {}
void initialize() {
int n;
scanf("%d", &n);
for(int i = 0; i < n; i++) {
int x;
scanf("%d", &x);
ListNode *node = new ListNode(x);
if(head == NULL) {
head = tail = node;
}
else {
tail->next = node;
tail = node;
}
size++;
}
}
void insert(int i, int x) {
if(i < 0 || i > size) return;
ListNode *node = new ListNode(x);
if(i == 0) {
node->next = head;
head = node;
if(tail == NULL) tail = head;
}
else if(i == size) {
tail->next = node;
tail = node;
}
else {
ListNode *cur = head;
for(int j = 0; j < i - 1; j++) {
cur = cur->next;
}
node->next = cur->next;
cur->next = node;
}
size++;
}
void erase(int i) {
if(i < 0 || i >= size) return;
ListNode *cur = head, *pre = NULL;
for(int j = 0; j < i; j++) {
pre = cur;
cur = cur->next;
}
if(pre == NULL) {
head = head->next;
if(head == NULL) tail = NULL;
}
else {
pre->next = cur->next;
if(pre->next == NULL) tail = pre;
}
delete cur;
size--;
}
void swap() {
if(size <= 2) return;
ListNode *cur = head, *pre = NULL;
while(cur && cur->next) {
ListNode *tmp = cur;
cur = cur->next;
tmp->next = cur->next;
cur->next = tmp;
if(pre) pre->next = cur;
pre = tmp;
cur = tmp->next;
}
if(size % 2 == 0) tail = pre;
}
void moveback(int i, int x) {
if(i <= 0 || i > size) return;
ListNode *cur = head, *pre = NULL;
for(int j = 0; j < i - 1; j++) {
pre = cur;
cur = cur->next;
}
for(int j = 0; j < x; j++) {
if(cur == NULL) cur = head;
ListNode *tmp = cur->next;
if(pre == NULL) {
head = tmp;
tail->next = cur;
cur->next = NULL;
tail = cur;
}
else if(tmp == NULL) {
pre->next = NULL;
tail = pre;
cur->next = head;
head = cur;
}
else {
pre->next = tmp;
cur->next = tmp->next;
tmp->next = cur;
}
pre = cur;
cur = cur->next;
}
}
int query(int i) {
if(i < 1 || i > size) return -1;
ListNode *cur = head;
for(int j = 1; j < i; j++) {
cur = cur->next;
}
return cur->val;
}
void printAll() {
ListNode *cur = head;
while(cur) {
printf("%d ", cur->val);
cur = cur->next;
}
printf("\n");
}
void clearMemory() {
ListNode *cur = head;
while(cur) {
ListNode *tmp = cur;
cur = cur->next;
delete tmp;
}
head = tail = NULL;
size = 0;
}
};
int main() {
LinkedList list;
int m, op, i, x;
list.initialize();
scanf("%d", &m);
while(m--) {
scanf("%d", &op);
if(op == 1) {
scanf("%d%d", &i, &x);
list.insert(i, x);
}
else if(op == 2) {
scanf("%d", &i);
list.erase(i);
}
else if(op == 3) {
list.swap();
}
else if(op == 4) {
scanf("%d%d", &i, &x);
list.moveback(i, x);
}
else if(op == 5) {
scanf("%d", &i);
printf("%d\n", list.query(i));
}
else if(op == 6) {
list.printAll();
}
}
list.clearMemory();
return 0;
}
```
class ListNode { public: ListNode(int x) : val(x), next(NULL) {} int val; ListNode *next; };请根据这个结构体,给出该链表增删改查的代码
链表的增删改查代码如下:
// 增加节点
void addNode(ListNode* &head, int x) {
ListNode* newNode = new ListNode(x);
if (head == NULL) {
head = newNode;
} else {
ListNode* cur = head;
while (cur->next != NULL) {
cur = cur->next;
}
cur->next = newNode;
}
}
// 删除节点
void deleteNode(ListNode* &head, int x) {
ListNode* cur = head;
ListNode* pre = NULL;
while (cur != NULL) {
if (cur->val == x) {
if (pre == NULL) {
head = cur->next;
} else {
pre->next = cur->next;
}
delete cur;
return;
}
pre = cur;
cur = cur->next;
}
}
// 修改节点
void modifyNode(ListNode* &head, int x, int y) {
ListNode* cur = head;
while (cur != NULL) {
if (cur->val == x) {
cur->val = y;
return;
}
cur = cur->next;
}
}
// 查找节点
ListNode* searchNode(ListNode* head, int x) {
ListNode* cur = head;
while (cur != NULL) {
if (cur->val == x) {
return cur;
}
cur = cur->next;
}
return NULL;
}