csdn c语言实现八数码问题

八数码问题是一种经典的人工智能问题，可以使用深度优先搜索、广度优先搜索、A*算法等多种算法来解决。以下是一个基于C语言的八数码问题求解程序：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define MAX_QUEUE_SIZE 1000   // 队列最大长度
#define MAX_STEP 100          // 最大步数

// 八数码状态结构体
typedef struct {
    int board[3][3];           // 棋盘状态
    int zero_row;              // 空格所在行
    int zero_col;              // 空格所在列
    char path[MAX_STEP + 1];   // 路径
} State;

// 队列结构体
typedef struct {
    State data[MAX_QUEUE_SIZE];   // 数据
    int front;                    // 队首指针
    int rear;                     // 队尾指针
} Queue;

// 初始化队列
void init_queue(Queue *queue) {
    queue->front = 0;
    queue->rear = 0;
}

// 判断队列是否为空
int is_queue_empty(Queue *queue) {
    return queue->front == queue->rear;
}

// 判断队列是否已满
int is_queue_full(Queue *queue) {
    return (queue->rear + 1) % MAX_QUEUE_SIZE == queue->front;
}

// 入队
void enqueue(Queue *queue, State state) {
    if (is_queue_full(queue)) {
        fprintf(stderr, "Error: queue is full\n");
        exit(1);
    }

    queue->data[queue->rear] = state;
    queue->rear = (queue->rear + 1) % MAX_QUEUE_SIZE;
}

// 出队
State dequeue(Queue *queue) {
    if (is_queue_empty(queue)) {
        fprintf(stderr, "Error: queue is empty\n");
        exit(1);
    }

    State state = queue->data[queue->front];
    queue->front = (queue->front + 1) % MAX_QUEUE_SIZE;
    return state;
}

// 初始化状态
void init_state(State *state) {
    int i, j, k;

    for (i = 0, k = 1; i < 3; i++) {
        for (j = 0; j < 3; j++, k++) {
            state->board[i][j] = k % 9;
            if (k % 9 == 0) {
                state->board[i][j] = 0;
                state->zero_row = i;
                state->zero_col = j;
            }
        }
    }

    state->path[0] = '\0';
}

// 复制状态
void copy_state(State *dest, State *src) {
    memcpy(dest->board, src->board, sizeof(src->board));
    dest->zero_row = src->zero_row;
    dest->zero_col = src->zero_col;
    strcpy(dest->path, src->path);
}

// 交换两个位置的值
void swap(int *a, int *b) {
    int temp = *a;
    *a = *b;
    *b = temp;
}

// 移动空格
void move(State *state, int row, int col) {
    swap(&state->board[state->zero_row][state->zero_col], &state->board[row][col]);
    state->zero_row = row;
    state->zero_col = col;
}

// 判断状态是否合法
int is_valid_state(State *state) {
    int i, j, k, count = 0;

    for (i = 0; i < 3; i++) {
        for (j = 0; j < 3; j++) {
            k = state->board[i][j];
            if (k == 0) {
                continue;
            }
            count++;
            if (k != i * 3 + j + 1) {
                return 0;
            }
        }
    }

    return count == 8;
}

// 打印状态
void print_state(State *state) {
    int i, j;

    for (i = 0; i < 3; i++) {
        for (j = 0; j < 3; j++) {
            printf("%d ", state->board[i][j]);
        }
        printf("\n");
    }

    printf("%s\n", state->path);
}

// 深度优先搜索
int dfs(State *state, int depth, int max_depth) {
    if (depth == max_depth) {
        return 0;
    }

    if (is_valid_state(state)) {
        print_state(state);
        return 1;
    }

    State next_state;
    int i;

    // 向上移动
    if (state->zero_row > 0) {
        copy_state(&next_state, state);
        move(&next_state, state->zero_row - 1, state->zero_col);
        next_state.path[depth] = 'U';
        next_state.path[depth + 1] = '\0';
        if (dfs(&next_state, depth + 1, max_depth)) {
            return 1;
        }
    }

    // 向下移动
    if (state->zero_row < 2) {
        copy_state(&next_state, state);
        move(&next_state, state->zero_row + 1, state->zero_col);
        next_state.path[depth] = 'D';
        next_state.path[depth + 1] = '\0';
        if (dfs(&next_state, depth + 1, max_depth)) {
            return 1;
        }
    }

    // 向左移动
    if (state->zero_col > 0) {
        copy_state(&next_state, state);
        move(&next_state, state->zero_row, state->zero_col - 1);
        next_state.path[depth] = 'L';
        next_state.path[depth + 1] = '\0';
        if (dfs(&next_state, depth + 1, max_depth)) {
            return 1;
        }
    }

    // 向右移动
    if (state->zero_col < 2) {
        copy_state(&next_state, state);
        move(&next_state, state->zero_row, state->zero_col + 1);
        next_state.path[depth] = 'R';
        next_state.path[depth + 1] = '\0';
        if (dfs(&next_state, depth + 1, max_depth)) {
            return 1;
        }
    }

    return 0;
}

// 广度优先搜索
void bfs(State *state) {
    Queue queue;
    init_queue(&queue);
    enqueue(&queue, *state);

    while (!is_queue_empty(&queue)) {
        State cur_state = dequeue(&queue);
        if (is_valid_state(&cur_state)) {
            print_state(&cur_state);
            return;
        }

        State next_state;
        int i;

        // 向上移动
        if (cur_state.zero_row > 0) {
            copy_state(&next_state, &cur_state);
            move(&next_state, cur_state.zero_row - 1, cur_state.zero_col);
            next_state.path[strlen(cur_state.path)] = 'U';
            next_state.path[strlen(cur_state.path) + 1] = '\0';
            enqueue(&queue, next_state);
        }

        // 向下移动
        if (cur_state.zero_row < 2) {
            copy_state(&next_state, &cur_state);
            move(&next_state, cur_state.zero_row + 1, cur_state.zero_col);
            next_state.path[strlen(cur_state.path)] = 'D';
            next_state.path[strlen(cur_state.path) + 1] = '\0';
            enqueue(&queue, next_state);
        }

        // 向左移动
        if (cur_state.zero_col > 0) {
            copy_state(&next_state, &cur_state);
            move(&next_state, cur_state.zero_row, cur_state.zero_col - 1);
            next_state.path[strlen(cur_state.path)] = 'L';
            next_state.path[strlen(cur_state.path) + 1] = '\0';
            enqueue(&queue, next_state);
        }

        // 向右移动
        if (cur_state.zero_col < 2) {
            copy_state(&next_state, &cur_state);
            move(&next_state, cur_state.zero_row, cur_state.zero_col + 1);
            next_state.path[strlen(cur_state.path)] = 'R';
            next_state.path[strlen(cur_state.path) + 1] = '\0';
            enqueue(&queue, next_state);
        }
    }
}

int main() {
    State state;
    init_state(&state);
    bfs(&state);
    return 0;
}

以上程序实现了八数码问题的解法，可以通过深度优先搜索或广度优先搜索来求解。其中深度优先搜索使用了递归实现，广度优先搜索使用了队列实现。