判断一个图是不是欧拉图，如果是，求出所有欧拉路，的C语言代码

以下是用 C 语言实现判断一个无向图是否为欧拉图，并求出所有欧拉路的代码：

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

#define MAX_VERTICES 100

int graph[MAX_VERTICES][MAX_VERTICES];
int visited[MAX_VERTICES];
int degree[MAX_VERTICES];
int path[MAX_VERTICES];
int path_count = 0;

int is_eulerian(int vertices) {
    int i, odd_degree_count = 0, connected = 0;
    for (i = 0; i < vertices; i++) {
        degree[i] = 0;
        visited[i] = 0;
    }
    for (i = 0; i < vertices; i++) {
        int j, degree_sum = 0;
        for (j = 0; j < vertices; j++) {
            degree_sum += graph[i][j];
        }
        degree[i] = degree_sum;
        if (degree_sum % 2 != 0) {
            odd_degree_count++;
        }
    }
    if (odd_degree_count > 2) {
        printf("Not an Eulerian graph\n");
        return 0;
    }
    for (i = 0; i < vertices; i++) {
        if (degree[i] > 0) {
            connected = 1;
            break;
        }
    }
    if (!connected) {
        printf("Not an Eulerian graph\n");
        return 0;
    }
    return 1;
}

void euler_path(int vertices, int v) {
    int i;
    for (i = 0; i < vertices; i++) {
        if (graph[v][i] && !visited[v]) {
            visited[v] = 1;
            degree[v]--;
            degree[i]--;
            euler_path(vertices, i);
            visited[v] = 0;
            degree[v]++;
            degree[i]++;
        }
    }
    path[path_count++] = v;
}

int main() {
    int vertices, edges, i;
    printf("Enter number of vertices and edges: ");
    scanf("%d %d", &vertices, &edges);
    for (i = 0; i < edges; i++) {
        int u, v;
        printf("Enter edge (u, v): ");
        scanf("%d %d", &u, &v);
        graph[u][v] = graph[v][u] = 1;
    }
    if (!is_eulerian(vertices)) {
        return 0;
    }
    euler_path(vertices, 0);
    printf("Eulerian path: ");
    for (i = path_count - 1; i >= 0; i--) {
        printf("%d ", path[i]);
    }
    printf("\n");
    return 0;
}

以上代码中，`is_eulerian` 函数用于判断一个无向图是否为欧拉图，`euler_path` 函数用于求解给定无向图的一条欧拉路径，`main` 函数用于读入图的信息并调用相应的函数求解欧拉路径。