Seven Puzzle (Aizu 0121 反向搜索bfs)

来源：互联网发布：淘宝店铺视频上传失败? 编辑：程序博客网时间：2024/05/08 11:39

这段时间要转向搜索了，图论先缓一缓，但也不能完全放了，得带着刷图论。把峰峰博客上的搜索刷一遍。这一题具体看：点击打开链接

代码：

#include <iostream>#include <functional>#include <cstdio>#include <cstring>#include <algorithm>#include <cmath>#include <string>#include <map>#include <stack>#include <vector>#include <set>#include <queue>#pragma comment (linker,"/STACK:102400000,102400000")#define pi acos(-1.0)#define eps 1e-6#define lson rt<<1,l,mid#define rson rt<<1|1,mid+1,r#define FRE(i,a,b)  for(i = a; i <= b; i++)#define FREE(i,a,b) for(i = a; i >= b; i--)#define FRL(i,a,b)  for(i = a; i < b; i++)#define FRLL(i,a,b) for(i = a; i > b; i--)#define mem(t, v)   memset ((t) , v, sizeof(t))#define sf(n)       scanf("%d", &n)#define sff(a,b)    scanf("%d %d", &a, &b)#define sfff(a,b,c) scanf("%d %d %d", &a, &b, &c)#define pf          printf#define DBG         pf("Hi\n")typedef long long ll;using namespace std;#define INF 0x3f3f3f3f#define mod 1000000009const int maxn = 1005;const int MAXN = 2005;const int MAXM = 200010;const int N = 1005;struct Node{    int x,y,step;    int g[2][4];};int dir[4][2]={0,1,1,0,-1,0,0,-1};int fac[]={1,1,2,6,24,120,720,5040,40320,362880};int a[10];int vis[50000];bool isok(int x,int y){    if (x>=0&&x<2&&y>=0&&y<4) return true;    return false;}int cantor(int w[][4]){    int s[8],cc=0;    for (int i=0;i<2;i++)        for (int j=0;j<4;j++)            s[cc++]=w[i][j];    int sum=0;    for (int i=0;i<8;i++)    {        int t=0;        for (int j=i+1;j<8;j++)        {            if (s[i]>s[j])                t++;        }        sum+=(t*fac[8-i-1]);    }    return sum;}void bfs(){    Node st,now;    queue<Node>Q;    for (int i=0;i<8;i++)        st.g[i/4][i%4]=i;    st.step=0;    st.x=st.y=0;    vis[cantor(st.g)]=0;    Q.push(st);    while (!Q.empty())    {        st=Q.front();        Q.pop();        for (int i=0;i<4;i++)        {            now.x=st.x+dir[i][0];            now.y=st.y+dir[i][1];            now.step=st.step+1;            if (isok(now.x,now.y))            {                for (int j=0;j<2;j++)                    for (int t=0;t<4;t++)                        now.g[j][t]=st.g[j][t];                swap(now.g[now.x][now.y],now.g[st.x][st.y]);                int cc=cantor(now.g);                if (vis[cc]!=-1) continue;                vis[cc]=now.step;                Q.push(now);            }        }    }    return ;}int main(){//#ifndef ONLINE_JUDGE//    freopen("C:/Users/lyf/Desktop/IN.txt","r",stdin);//#endif    int i,j;    memset(vis,-1,sizeof(vis));    bfs();    while (~scanf("%d",&a[0]))    {        for (i=1;i<8;i++)            scanf("%d",&a[i]);        Node st;        for (int i=0;i<8;i++)            st.g[i/4][i%4]=a[i];        int p=cantor(st.g);        printf("%d\n",vis[p]);    }    return 0;}

0 0