[BFS]1697번 숨바꼭질

문제링크 : https://www.acmicpc.net/problem/1697

#include<iostream>
#include<queue>
using namespace std;
 
int n, k;
int visited[100001] = { 0, };
 
int bfs(int start) {
    queue<int> q;
    q.push(start);
    visited[start] = 1;
    while (!q.empty()) {
        int y = q.front();
        q.pop();
        if (y == k) {
            return visited[y] - 1;
        }
        if (y - 1 <= 100000 && visited[y - 1] == 0) {
            visited[y - 1] = visited[y] + 1;
            q.push(y - 1);
        }
        if (y + 1 <= 100000 && visited[y + 1] == 0) {
            visited[y + 1] = visited[y] + 1;
            q.push(y + 1);
        }
        if (y *2 <= 100000 && visited[y*2] == 0) {
            visited[y *2] = visited[y] + 1;
            q.push(y *2);
        }
    }
}
 
int main() {
    scanf_s("%d %d", &n, &k);
 
    printf("%d",bfs(n));
    return 0;
}