public T DeQueue() { /********** Begin *********/ return null; /********** End *********/ }
时间: 2023-09-04 12:11:00 浏览: 38
As an AI language model, I cannot provide a complete implementation without more context about the data structure being used for the queue. However, in general, the DeQueue() method should remove and return the first element in the queue.
Here's an example implementation of a DeQueue() method using a LinkedList as the underlying data structure:
```
public T DeQueue() {
if (size == 0) {
throw new NoSuchElementException("Queue is empty");
}
T data = linkedList.getFirst();
linkedList.removeFirst();
size--;
return data;
}
```
Note that this implementation throws an exception if the queue is empty, and also updates the size of the queue accordingly.
相关问题
八数码问题a*算法c语言
八数码问题是一种经典的搜索问题,可以使用A*算法进行求解。A*算法是一种启发式搜索算法,能够在搜索过程中有针对性地搜索最优解,减小搜索空间,提高搜索效率。
以下是使用C语言实现八数码问题A*算法的示例代码:
```c
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define N 3
// 定义状态结构体
typedef struct state {
int board[N][N]; // 棋盘状态
int f; // f = g + h,g为从起始状态到当前状态的代价,h为从当前状态到目标状态的估价函数值
int g; // g为从起始状态到当前状态的代价
int h; // h为从当前状态到目标状态的估价函数值
int x; // 空格所在行
int y; // 空格所在列
struct state *parent; // 父状态指针
} state_t;
// 定义状态队列节点结构体
typedef struct node {
state_t *data; // 队列节点数据为状态指针
int priority; // 节点优先级,即状态f值
struct node *next; // 指向下一个节点的指针
} node_t;
// 定义状态队列结构体
typedef struct queue {
node_t *front; // 队列头指针
node_t *rear; // 队列尾指针
} queue_t;
// 初始化状态队列
void init_queue(queue_t *q) {
q->front = q->rear = NULL;
}
// 判断状态队列是否为空
int is_empty(queue_t *q) {
return q->front == NULL;
}
// 向状态队列添加状态
void enqueue(queue_t *q, state_t *s) {
node_t *new_node = (node_t *)malloc(sizeof(node_t));
new_node->data = s;
new_node->priority = s->f;
new_node->next = NULL;
if (q->rear == NULL) {
q->front = q->rear = new_node;
} else {
node_t *p = q->front;
node_t *prev = NULL;
while (p != NULL && p->priority <= new_node->priority) {
prev = p;
p = p->next;
}
if (prev == NULL) {
new_node->next = q->front;
q->front = new_node;
} else if (p == NULL) {
q->rear->next = new_node;
q->rear = new_node;
} else {
new_node->next = prev->next;
prev->next = new_node;
}
}
}
// 从状态队列中取出状态
state_t *dequeue(queue_t *q) {
if (q->front == NULL) {
return NULL;
} else {
node_t *p = q->front;
state_t *s = p->data;
q->front = q->front->next;
if (q->front == NULL) {
q->rear = NULL;
}
free(p);
return s;
}
}
// 判断状态是否为目标状态
int is_goal(state_t *s) {
int i, j, num = 1;
for (i = 0; i < N; i++) {
for (j = 0; j < N; j++) {
if (s->board[i][j] != num && !(i == N - 1 && j == N - 1 && s->board[i][j] == 0)) {
return 0;
}
num++;
}
}
return 1;
}
// 计算状态的估价函数值
int heuristic(state_t *s) {
int i, j, k, l, num, dist = 0;
for (i = 0; i < N; i++) {
for (j = 0; j < N; j++) {
num = s->board[i][j];
if (num == 0) {
continue;
}
k = (num - 1) / N;
l = (num - 1) % N;
dist += abs(i - k) + abs(j - l);
}
}
return dist;
}
// 复制状态
state_t *copy_state(state_t *s) {
state_t *new_state = (state_t *)malloc(sizeof(state_t));
memcpy(new_state->board, s->board, sizeof(s->board));
new_state->f = s->f;
new_state->g = s->g;
new_state->h = s->h;
new_state->x = s->x;
new_state->y = s->y;
new_state->parent = s->parent;
return new_state;
}
// 生成子状态
void generate_successors(state_t *s, queue_t *q) {
int i, j, tx, ty;
state_t *new_state;
for (i = -1; i <= 1; i++) {
for (j = -1; j <= 1; j++) {
if (i == 0 && j == 0) {
continue;
}
tx = s->x + i;
ty = s->y + j;
if (tx < 0 || tx >= N || ty < 0 || ty >= N) {
continue;
}
new_state = copy_state(s);
new_state->board[s->x][s->y] = s->board[tx][ty];
new_state->board[tx][ty] = 0;
new_state->x = tx;
new_state->y = ty;
new_state->g++;
new_state->h = heuristic(new_state);
new_state->f = new_state->g + new_state->h;
new_state->parent = s;
enqueue(q, new_state);
}
}
}
// 输出状态
void print_state(state_t *s) {
int i, j;
printf("f=%d, g=%d, h=%d\n", s->f, s->g, s->h);
for (i = 0; i < N; i++) {
for (j = 0; j < N; j++) {
printf("%d ", s->board[i][j]);
}
printf("\n");
}
}
// 输出解路径
void print_solution(state_t *s) {
if (s->parent != NULL) {
print_solution(s->parent);
}
print_state(s);
}
// 释放状态队列节点内存
void free_queue_node(node_t *p) {
if (p != NULL) {
free_queue_node(p->next);
free(p->data);
free(p);
}
}
// 释放状态队列内存
void free_queue(queue_t *q) {
free_queue_node(q->front);
}
// A*算法求解八数码问题
void solve(state_t *start) {
queue_t open;
state_t *s, *goal = NULL;
init_queue(&open);
start->g = 0;
start->h = heuristic(start);
start->f = start->g + start->h;
start->parent = NULL;
enqueue(&open, start);
while (!is_empty(&open)) {
s = dequeue(&open);
if (is_goal(s)) {
goal = s;
break;
}
generate_successors(s, &open);
}
if (goal != NULL) {
printf("Solution found:\n");
print_solution(goal);
} else {
printf("No solution.\n");
}
free_queue(&open);
}
int main() {
state_t start = {
{{1, 2, 3}, {4, 0, 5}, {6, 7, 8}},
0, 0, 0, 1, 1, NULL
};
solve(&start);
return 0;
}
```
以上代码实现了八数码问题A*算法的求解,代码中使用了状态队列优化搜索效率。在代码中,我们需要定义状态结构体,其中包含了当前棋盘状态、从起始状态到当前状态的代价g、从当前状态到目标状态的估价函数值h、状态f值、空格所在位置以及父状态指针。我们还需要定义状态队列节点结构体和状态队列结构体,以实现状态队列的操作。代码中使用了启发式函数h(n) = 曼哈顿距离来计算状态的估价函数值。
在main函数中,我们定义了起始状态,并调用solve函数求解八数码问题。在solve函数中,我们首先初始化状态队列,并将起始状态加入队列。然后循环取出队列头部的状态,如果该状态为目标状态,则搜索结束;否则,生成该状态的所有子状态,并将其加入状态队列中。最后,输出解路径或提示无解,并释放状态队列内存。
注意,上述代码仅为示例代码,可能存在不足之处,请以实际应用为准。
c++动态分配的char*队列
您好!关于动态分配的char*队列,您可以考虑使用链表来实现。具体的实现步骤可以参考下面的代码:
```
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
// 节点结构体
typedef struct node {
char* data; // 数据域
struct node* next; // 指针域
} Node;
// 队列结构体
typedef struct queue {
Node* front; // 队头指针
Node* rear; // 队尾指针
} Queue;
// 初始化队列
void initQueue(Queue* q) {
q->front = q->rear = NULL;
}
// 判断队列是否为空
int isEmptyQueue(Queue* q) {
return q->front == NULL;
}
// 入队操作
void enQueue(Queue* q, char* data) {
Node* newNode = (Node*)malloc(sizeof(Node));
newNode->data = (char*)malloc(strlen(data) + 1);
strcpy(newNode->data, data);
newNode->next = NULL;
if (isEmptyQueue(q)) {
q->front = q->rear = newNode;
} else {
q->rear->next = newNode;
q->rear = newNode;
}
}
// 出队操作
char* deQueue(Queue* q) {
if (isEmptyQueue(q)) {
return NULL;
}
Node* temp = q->front;
char* data = temp->data;
q->front = q->front->next;
if (q->front == NULL) {
q->rear = NULL;
}
free(temp);
return data;
}
// 测试代码
int main() {
Queue q;
initQueue(&q);
enQueue(&q, "Hello");
enQueue(&q, "World");
enQueue(&q, "ChitGPT");
while (!isEmptyQueue(&q)) {
printf("%s ", deQueue(&q));
}
return 0;
}
```
上述代码中使用了链表来实现队列,并且为每个节点的数据域动态分配了内存空间。您可以根据自己的实际需求对代码进行修改。希望对您有所帮助!