hdu4771 Stealing Harry Potter's Precious(DFS,BFS)

练习dfs和bfs的好题。

#include<iostream>
#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<string>
#include<cmath>
#include<map>
#include<set>
#include<vector>
#include<algorithm>
#include<stack>
#include<queue>
#include<cctype>
#include<sstream>
using namespace std;
#define pii pair<int,int>
#define LL long long int
const int eps=1e-;
const int INF=;
const int maxnm=+;
int ans,n,m,k,d[][];
int dx[]= {,-,,};
int dy[]= {,,,-};
char maps[maxnm][maxnm];
int had[maxnm][maxnm];
struct Precious
{
    int x,y;
    bool used;
} p[];
int Bfs(int from,int to);
bool Dfs(int id,int now,int step);
void ini();
int main()
{
    //freopen("in8.txt","r",stdin);
    while(scanf("%d%d",&n,&m)==)
    {
        if(n==&&m==) break;
        ini();
        for(int i=; i<=n; i++)
        {
            for(int j=; j<=m; j++)
            {
                cin>>maps[i][j];
                if(maps[i][j]=='@')
                {
                    p[].x=i;
                    p[].y=j;
                }
            }
        }
        scanf("%d",&k);
        for(int i=; i<=k; i++)
        {
            int xx,yy;
            scanf("%d%d",&xx,&yy);
            p[i].x=xx;
            p[i].y=yy;
        }
        if(Dfs(,,))
        {
            printf("%d\n",ans);
        }
        else
        {
            printf("-1\n");
        }
    }
    return ;
}
void ini()
{
    memset(d,-,sizeof(d));
    ans=INF;
    for(int i=; i<; i++)
    {
        p[i].used=;
    }
}
int Bfs(int from,int to)
{
    if(d[from][to]!=-) return d[from][to];
    if((p[from].x==p[to].x)&&(p[from].y==p[to].y))
    {
        return d[from][to]=;
    }
    else
    {
        queue<pii>q;
        memset(had,,sizeof(had));
        q.push(make_pair(p[from].x,p[from].y));
        had[p[from].x][p[from].y]=;
        while(!q.empty())
        {
            int tx=q.front().first;
            int ty=q.front().second;
            q.pop();
            for(int i=; i<; i++)
            {
                int X=tx+dx[i];
                int Y=ty+dy[i];
                if(X>=&&X<=n&&Y>=&&Y<=m)
                {
                    if(had[X][Y]||maps[X][Y]=='#')
                    {
                        continue;
                    }
                    else
                    {
                        q.push(make_pair(X,Y));
                        had[X][Y]=had[tx][ty]+;
                        if(X==p[to].x&&Y==p[to].y)
                        {
                            return d[from][to]=had[X][Y]-;
                        }
                    }
                }
            }
        }
        return d[from][to]=-;
    }
}

bool Dfs(int id,int now,int step)
//id表示现在在哪点，now表示已经拿了几个，step表示目前一共走了几步
{
    bool w=;
    p[id].used=;
    if(now==k)
    {
        //cout<<"***"<<step<<endl;
        ans=min(ans,step);
        p[id].used=;
        return true;
    }
    else
    {
        for(int i=; i<=k; i++)
        {
            if(p[i].used==)
            {
                int stt=Bfs(id,i);
                if(stt==-)
                {
                    p[id].used=;
                    return false;
                }
                else
                {
                    if(Dfs(i,now+,step+stt))
                    {
                        w=;
                    }
                }
            }
        }
        if(w==)
        {
            p[id].used=;
            return true;
        }
        else
        {
            p[id].used=;
            return false;
        }
    }
}