poj3278（bfs）

分析：广搜，每次三种情况枚举一下，太水不多说了。
#include <cstdio>

#include <cstring>

#include <cmath>

#include <iostream>

#include <algorithm>

#include <queue>

#include <cstdlib>

#include <vector>

#include <set>

#include <map>

#define LL long long

#define mod 1000000007

#define inf 0x3f3f3f3f

#define N 100010

using namespace std;

struct node

{

    int x,step;

    bool operator<(const node a)const

    {

        return step>a.step;

    }

};

priority_queue<node>que;

int vis[N];

int judge(int x)

{

    return x>=&&x<=;

}

node make_node(int a,int b)

{

    node temp;

    temp.x=a;temp.step=b;

    return temp;

}

int main()

{

    int n,k;

    while(scanf("%d%d",&n,&k)>)

    {

        memset(vis,,sizeof(vis));

        while(!que.empty())que.pop();

        que.push(make_node(n,));

        vis[n]=;

        int ans=;

        while(!que.empty())

        {

            node now=que.top();

            que.pop();

            int x=now.x;//printf("%d %d\n",now.x,now.step);

            if(x==k)

            {

                ans=now.step;

                break;

            }

            if(judge(x+)&&!vis[x+])

            {

                vis[x+]=;que.push(make_node(x+,now.step+));

            }

            if(judge(x-)&&!vis[x-])

            {

                vis[x-]=;que.push(make_node(x-,now.step+));

            }

            if(judge(*x)&&!vis[x*])

            {

                vis[x*]=;que.push(make_node(*x,now.step+));

            }

        }

        printf("%d\n",ans);

    }

}
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