帮我写个用c++导入个txt用迪杰斯特拉写个算法

好的，以下是一个简单的用C语言实现Dijkstra算法的例子，实现从一个txt文件中读取图的信息。

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

#define MAX_VERTEX 100

int graph[MAX_VERTEX][MAX_VERTEX];
int dist[MAX_VERTEX];
int visited[MAX_VERTEX];

int num_vertex;

int get_min_distance() {
    int min_distance = INT_MAX;
    int min_vertex = -1;
    for (int i = 0; i < num_vertex; i++) {
        if (!visited[i] && dist[i] < min_distance) {
            min_distance = dist[i];
            min_vertex = i;
        }
    }
    return min_vertex;
}

void dijkstra(int start) {
    for (int i = 0; i < num_vertex; i++) {
        dist[i] = INT_MAX;
        visited[i] = 0;
    }
    dist[start] = 0;
    for (int i = 0; i < num_vertex; i++) {
        int u = get_min_distance();
        visited[u] = 1;
        for (int v = 0; v < num_vertex; v++) {
            if (graph[u][v] && !visited[v] && dist[u] != INT_MAX && dist[u] + graph[u][v] < dist[v]) {
                dist[v] = dist[u] + graph[u][v];
            }
        }
    }
}

int main() {
    FILE *fp;
    if ((fp = fopen("graph.txt", "r")) == NULL) {
        fprintf(stderr, "Can't open graph.txt file!\n");
        exit(EXIT_FAILURE);
    }

    // 读取图的信息
    fscanf(fp, "%d", &num_vertex);
    for (int i = 0; i < num_vertex; i++) {
        for (int j = 0; j < num_vertex; j++) {
            fscanf(fp, "%d", &graph[i][j]);
        }
    }

    // 可以从任意节点开始
    int start = 0;
    dijkstra(start);

    // 输出最短路径
    printf("Shortest distances from vertex %d:\n", start);
    for (int i = 0; i < num_vertex; i++) {
        printf("Vertex %d: %d\n", i, dist[i]);
    }

    fclose(fp);
    return 0;
}

该代码首先从名为"graph.txt"的文件中读取图的信息，然后从任意节点开始计算最短路径，并输出到控制台上。请注意，此代码仅用于演示用途，不适用于大型图形。