By yusijia

Updated:

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#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <iostream>
#include <queue>

using namespace std;

const int N = 100;//默认最大顶点数
const int M = 10000;//默认最大边数

int n, m;
int head[N];
bool vis[N];
queue <int> que;

struct EdgeNode{
    int to;
    int w;
    int next;
};

EdgeNode Edge[M];

void init()
{
    memset(head, -1, sizeof(head));
    memset(vis, false, sizeof(vis));
}

void input()
{
    cin >> n >> m;
    int i, j, w;

    for(int k = 1; k <= m; k++){
        cin >> i >> j; //>>w
        Edge[k].to = j;
	//Edge[k].to = w;
        Edge[k].next = head[i];
        head[i] = k;
    }
}

void BFS()
{
    que.push(1);
    int i, k;
    while(!que.empty())
    {
        if (vis[que.front()])
        {
            que.pop();
            continue;
        }
        vis[que.front()] = true;
        for(k = head[que.front()]; ~k; k = Edge[k].next)
        {
            if(!vis[Edge[k].to]){
                que.push(Edge[k].to);
                //printf("to : %d\n", Edge[k].to);
                //printf("size : %d", que.size());
            }
        }
        printf("%d\n", que.front());
        que.pop();
    }
}

int main()
{
    init();
    input();
    BFS();
    return 0;
}

//
输入：
5 4
1 3
1 2
1 5
3 4

输出：
1 5 2 3 4
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