코영방

https://www.acmicpc.net/problem/1260

1. 단계 : 시작 정점을 방문했다고 표시하고, Queue에 push

void bfs(int start){
    checked[start]=1;
    queue<int> q;
    q.push(start);
    while(!q.emplace()){
        
    }
}

2. 단계 
시작 정점을 방문했다고 표시하고, Queue에 push
Queue가 빌때까지 반복하면서, queue의 front값을 받고, pop함

void bfs(int start){
    checked[start]=1;
    queue<int> q;
    q.push(start);
    while(!q.empty()){
        int current = q.front();
        q.pop();
        printf("%d ", current);
    }
}

3. 단계
시작 정점을 방문했다고 표시하고, Queue에 push
Queue가 빌때까지 반복하면서, queue의 front값을 받고, pop함

queue의 front 정점(current)을 대상으로 연결된 정점(next)들을 찾음
next중에 방문하지 않은 정점이면, 방문 표시하고 queue에 push
이것을 queue가 빌때까지 반복

void bfs(int start){
    checked[start]=1;
    queue<int> q;
    q.push(start);
    while(!q.empty()){
        int current = q.front();
        q.pop();
        printf("%d ", current);
        for(int i=0; i<vxy[current].size(); i++){
            int next=vxy[current][i];
            if(checked[next] == 0){
                q.push(next);
                checked[next]=1;
            }
        }
    }
}

전체 소스코드

#include <bits/stdc++.h>
using namespace std;
int checked[10000];
vector<int>vxy[10000];

void dfs(int start)
{
    checked[start]=1;
    printf("%d ",start);
    for(int i=0; i<vxy[start].size(); i++){
        int next=vxy[start][i];
        if(checked[next] == 0){
            dfs(next);
        }
    }
}

void bfs(int start){
    checked[start]=1;
    queue<int> q;
    q.push(start);
    while(!q.empty()){
        int current = q.front();
        q.pop();
        printf("%d ", current);
        for(int i=0; i<vxy[current].size(); i++){
            int next=vxy[current][i];
            if(checked[next] == 0){
                q.push(next);
                checked[next]=1;
            }
        }
    }
}

int main() {
    int a,b,c,n,m,i;
    scanf("%d %d %d",&n,&m,&c);
    for(i=1; i<=m; i++){
        scanf("%d %d",&a,&b);
        vxy[a].push_back(b);
        vxy[b].push_back(a);
    }

    for(i=1; i<=n; i++){
        sort(vxy[i].begin(),vxy[i].end());
    }

    dfs(c);
    for(i=0; i<=n; i++)checked[i]=0;
    printf("\n");
    bfs(c);

    return 0;
}