c语言 最小二叉树 内容：（1）由给定的顶点和边的信息构造图的邻接矩阵存储； （2）对该图进行深度优先搜索，输出搜索得到的结点序列； 以邻接表作存储结构，用克鲁斯卡尔算法构造最小生成树。

抱歉，我之前的回答有误，最小二叉树其实是指最小生成树（Minimum Spanning Tree），以下是C语言下的实现。

1. 构造图的邻接矩阵存储

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

#define MAX_VERTICES 100

int graph[MAX_VERTICES][MAX_VERTICES];

void add_edge(int u, int v, int weight) {
    graph[u][v] = weight;
    graph[v][u] = weight;
}

int main() {
    int vertices, edges;
    scanf("%d%d", &vertices, &edges);
    for (int i = 0; i < edges; i++) {
        int u, v, weight;
        scanf("%d%d%d", &u, &v, &weight);
        add_edge(u, v, weight);
    }
    return 0;
}

2. 深度优先搜索

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

#define MAX_VERTICES 100

int graph[MAX_VERTICES][MAX_VERTICES];
bool visited[MAX_VERTICES];

void dfs(int u, int vertices) {
    visited[u] = true;
    printf("%d ", u);
    for (int v = 0; v < vertices; v++) {
        if (graph[u][v] && !visited[v]) {
            dfs(v, vertices);
        }
    }
}

int main() {
    int vertices, edges;
    scanf("%d%d", &vertices, &edges);
    for (int i = 0; i < edges; i++) {
        int u, v, weight;
        scanf("%d%d%d", &u, &v, &weight);
        add_edge(u, v, weight);
    }
    dfs(0, vertices);
    return 0;
}

3. 克鲁斯卡尔算法构造最小生成树

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

#define MAX_VERTICES 100
#define MAX_EDGES 100

struct edge {
    int u, v;
    int weight;
};

struct edge edges[MAX_EDGES];
int parent[MAX_VERTICES];
int rank[MAX_VERTICES];

int find(int x) {
    if (parent[x] != x) {
        parent[x] = find(parent[x]);
    }
    return parent[x];
}

void union_set(int x, int y) {
    int root_x = find(x);
    int root_y = find(y);
    if (root_x == root_y) {
        return;
    }
    if (rank[root_x] < rank[root_y]) {
        parent[root_x] = root_y;
    } else if (rank[root_x] > rank[root_y]) {
        parent[root_y] = root_x;
    } else {
        parent[root_x] = root_y;
        rank[root_y]++;
    }
}

int cmp(const void *a, const void *b) {
    return ((struct edge *)a)->weight - ((struct edge *)b)->weight;
}

int main() {
    int vertices, edges_num;
    scanf("%d%d", &vertices, &edges_num);

    for (int i = 0; i < edges_num; i++) {
        int u, v, weight;
        scanf("%d%d%d", &u, &v, &weight);
        edges[i].u = u;
        edges[i].v = v;
        edges[i].weight = weight;
    }

    qsort(edges, edges_num, sizeof(struct edge), cmp);

    for (int i = 0; i < vertices; i++) {
        parent[i] = i;
        rank[i] = 0;
    }

    int mst_edges = 0;
    for (int i = 0; i < edges_num; i++) {
        if (find(edges[i].u) != find(edges[i].v)) {
            union_set(edges[i].u, edges[i].v);
            mst_edges++;
            printf("%d %d %d\n", edges[i].u, edges[i].v, edges[i].weight);
            if (mst_edges == vertices - 1) {
                break;
            }
        }
    }

    return 0;
}