[백준 5014] 스타트 링크 (BFS) (C/C++)

#include <stdio.h>
#include <iostream>
#include <queue>
#include <vector>
#include <algorithm>
using namespace std;
 
int total, start, arrive, up, down;
int visited[1000010];
queue<int> q;
 
void BFS()
{
    visited[start] = 1;
    q.push(start);
    
    while(!q.empty())
    {
        int x = q.front();
        q.pop();
        
        for(int i = 1; i <= 2; i++)
        {
            int xpos;
            // up
            if(i == 1)
            {
                xpos = x + up;
            }
            // down
            else if(i == 2)
            {
                xpos = x - down;
            }
            
            if(xpos >= 1 && xpos <= total && visited[xpos] == 0)
            {
                visited[xpos] = visited[x] + 1;
                q.push(xpos);
            }
            
            if(xpos == arrive)
            {
                return;
            }
        }
    }
}
 
int main(void)
{
//    freopen("B5014_input.txt", "r", stdin);
    
    cin >> total >> start >> arrive >> up >> down;
    
    BFS();
    
    if(visited[arrive] == 0)
    {
        cout << "use the stairs";
    }
    else
    {
        cout << visited[arrive]-1;
    }
    
    return 0;
}