【HAOI 2008】 移动玩具

【题目链接】

           https://www.lydsy.com/JudgeOnline/problem.php?id=1054

【算法】

            广度优先搜索

【代码】

             

#include<bits/stdc++.h>
using namespace std;
const int dx[4] = {0,0,-1,1};
const int dy[4] = {-1,1,0,0};
const int MAXS = 1 << 16;

struct info
{
        int mp[5][5];
        int step;
} ;

int i,j,k,goal,tx,ty,l,r,state;
int mp[5][5],g[5][5];
info q[MAXS];
info cur,tmp;
bool visited[MAXS];

inline bool valid(int x,int y)
{
        return x > 0 && x <= 4 && y > 0 && y <= 4;
}
inline int get(int a[5][5])
{
        int i,j,ret = 0;
        int b = 1;
        for (i = 1; i <= 4; i++)
        {
                for (j = 1; j <= 4; j++)
                {
                        ret += a[i][j] * b;
                        b <<= 1;        
                }        
        }        
        return ret;
}

int main() 
{
        
        for (i = 1; i <= 4; i++)
        {
                for (j = 1; j <= 4; j++)
                {
                        mp[i][j] = getchar() - '0';        
                }        
                getchar();
        }
        getchar();
        for (i = 1; i <= 4; i++)
        {
                for (j = 1; j <= 4; j++)
                {
                        g[i][j] = getchar() - '0';
                }
                getchar();
        }
        goal = get(g);
        visited[get(mp)] = true;
        if (visited[goal])
        {
                printf("0\n");
                return 0;
        }
        l = r = 1;
        memcpy(q[1].mp,mp,sizeof(q[1].mp));
        q[1].step = 0;
        while (l <= r)
        {
                cur = q[l];
                l++;
                for (i = 1; i <= 4; i++)
                {
                        for (j = 1; j <= 4; j++)
                        {
                                if (cur.mp[i][j] == 1)
                                {
                                        for (k = 0; k < 4; k++)
                                        {
                                                tx = i + dx[k];
                                                ty = j + dy[k];
                                                if (valid(tx,ty) && cur.mp[tx][ty] == 0)
                                                {
                                                        swap(cur.mp[i][j],cur.mp[tx][ty]);
                                                        state = get(cur.mp);
                                                        if (!visited[state])
                                                        {
                                                                visited[state] = true;
                                                                if (state == goal) 
                                                                {
                                                                        printf("%d\n",cur.step+1);
                                                                        return 0;
                                                                }
                                                                r++;
                                                                memcpy(q[r].mp,cur.mp,sizeof(q[r].mp));
                                                                q[r].step = cur.step + 1;
                                                        }
                                                        swap(cur.mp[i][j],cur.mp[tx][ty]);
                                                }        
                                        }        
                                }    
                        }        
                }        
        }
        
        return 0;
    
}