算法与数据结构之广度优先搜索

#include<bits/stdc++.h>
using namespace std;
#define MAX 100
#define WHITE 0
#define GRAY 1
#define BLACK 2

int n;
int color[MAX+1];
int M[MAX+1][MAX+1];
int d[MAX+1];


void bfs()
{
    for(int i=0;i<=n;i++)
        d[i] = -1;
    queue<int>q;
    color[1] = GRAY;
    q.push(1);
    d[1] = 0;


    while(!q.empty())
    {
        int u = q.front();
        q.pop();
        color[u] = BLACK;
        for(int i=1;i<=n;i++)
        {
            if(color[i]==WHITE&&M[u][i]==1)
            {
                q.push(i);
                color[i] = GRAY;
                d[i] = d[u] + 1;
            }
        }
    }

    for(int i=1;i<=n;i++)
        cout<<i<<" "<<d[i]<<endl;
}

int main()
{
   cin>>n;
   for(int i=0;i<n;i++)
   {
        int u,k;
        cin>>u>>k;
        for(int j=0;j<k;j++)
        {
            int v;
            cin>>v;
            M[u][v] = 1;
        }
   }

   bfs();

}