bfs

bfs的简单应用：

#include <iostream>
#include <cstdio>
#include <cstring>
#include <queue>
#include <stack>

using namespace std;

int N, K;
int vis[100010];

struct node {
    int pos;
    int minute;
};

int bfs();

int main()
{
//    freopen("in.txt", "r", stdin);
//    freopen("out.txt", "w", stdout);

    cin>>N>>K;
    memset(vis, 0, sizeof(vis));
    cout<<bfs()<<endl;

    return 0;
}

int bfs()
{
    queue<node>Queue;
    node Node;
    Node.pos = N;
    Node.minute = 0;
    vis[Node.pos] = 1;
    Queue.push(Node);
    while (!Queue.empty()) {
        int x = Queue.front().pos;
        int y = Queue.front().minute;
//        cout<<x<<endl;
        Queue.pop();
        if (x == K) {
            return y;
        }
        if (x-1>=0 && (!vis[x-1])) {
            vis[x-1] = 1;
            Node.pos = x-1;
            Node.minute = y+1;
            Queue.push(Node);
        }
        if (x+1<=100000 && (!vis[x+1])) {
            vis[x+1] = 1;
            Node.pos = x+1;
            Node.minute = y+1;
            Queue.push(Node);
        }
        if (x*2<=100000 && (!vis[x*2])) {
            vis[x*2] = 1;
            Node.pos = x*2;
            Node.minute = y+1;
            Queue.push(Node);
        }
    }
    return 0;
}