1325번 효율적인 해킹

https://www.acmicpc.net/problem/1325

v[A].push_back(B);가 아니라

v[B].push_back(A);로 풀어야

더 간단히 풀 수 있다.

#include <iostream>
#include <queue>
#include <stack>
#include <cstdio>
#include <vector>
#include <cstring>
#include <string>
#include <math.h>
#include <algorithm>
#include <map>
 
using namespace std;
 
vector<int> v[10001];
 
int child[10001];
bool visit[10001];
 
int N = 0, M = 0;
 
void DFS(int start, int index)
{
    visit[start] = true;
 
    for (auto next : v[start])
    {
        if (!visit[next])
        {
            ++child[index];
 
            DFS(next, index);
        }
    }
}
 
int main(void)
{
    int A = 0, B = 0, Max = -1;
 
    memset(child, 0, sizeof(child));
 
    scanf("%d %d", &N, &M);
 
    for (int i = 0; i < M; i++)
    {
        scanf("%d %d", &A, &B);
 
        v[B].push_back(A);
    }
 
    for (int i = 1; i <= N; i++)
    {
        memset(visit, false, sizeof(visit));
 
        ++child[i];
        
        DFS(i, i);
 
        Max = max(Max, child[i]);
    }
 
    for (int i = 1; i <= N; i++)
    {
        if (child[i] == Max)
        {
            printf("%d ", i);
        }
    }
 
    printf("\n");
 
    return 0;
}