BOJ 2178 C++, bfs최단거리

코드

#include <bits/stdc++.h>
#define ll long long
using namespace std;
#define X first
#define Y second

string lev[101];
int dis[101][101];
int dx[4] = { 1,0,-1,0 };
int dy[4] = { 0,1,0,-1 };

int main(void) 
{
    ios::sync_with_stdio(0);
    cin.tie(0);
    int n, m; cin >> n >> m;

    for (int i = 0; i < n; i++)
    {
        cin >> lev[i];
        fill(dis[i], dis[i] + m, -1);
    }
       
    queue<pair<int, int>> q;
    dis[0][0] = 0;
    q.push({ 0,0 });
    while (!q.empty())
    {
        auto cur = q.front(); q.pop();
        for (int dir = 0; dir < 4; dir++)
        {
            int nx = cur.X + dx[dir];
            int ny = cur.Y + dy[dir];
            if (nx < 0 || ny < 0 || nx >= n || ny >= m) continue;
            if (dis[nx][ny] >= 0 || lev[nx][ny] != '1') continue;
            dis[nx][ny] = dis[cur.X][cur.Y] + 1;
            q.push({ nx,ny });
        }
    }
    cout << dis[n - 1][m - 1] + 1;
}

먼저 방문한놈이 dis를 초기화 시켰기 때문에 최단거리임