图（邻接矩阵版）

#include<iostream>
#include<algorithm>
#include<vector>
const int maxv = 1000;
const int inf = 1000000000;
int n, G[maxv][maxv];
bool vis[maxv] = { false };
void dfs(int u, int depth) {
    vis[u] = true;
    for (int v = 0; v < n; v++) {
        if (vis[v] == false && G[u][v] != inf) {
            dfs(v, depth + 1);
        }
    }
}
void dfstrave() {
    for (int u = 0; u < n; u++) {
        if (vis[u] == false) {
            dfs(u, 1);
        }
    }
}