UVA 11624 UVA 10047 两道用 BFS进行最短路搜索的题

#include <iostream>
#include <cstdio>
#include <cstring>
#include <queue>
using namespace std;
struct node{
int ft;
int sta;
}flo[1010][1010];
int vis[1010][1010];
struct person{
int x,y,t,fx,fy;
};
int R,C;
int dir[][2]={{0,1},{0,-1},{1,0},{-1,0}};
typedef pair<int,int> pill;
queue<pill> v;
queue<person> q;
void init()
{
memset(vis,0,sizeof vis);
while (!v.empty()){
pill x=v.front();
v.pop();
for (int i=0;i<4;i++){
int nx=x.first+dir[i][0];
int ny=x.second+dir[i][1];
int tmp=flo[x.first][x.second].ft+1;;
if (nx<0 || ny<0 || nx>=R || ny>=C) continue;
if (flo[nx][ny].ft>=0 && flo[nx][ny].ft<=tmp || flo[nx][ny].sta==0) continue;
flo[nx][ny].ft=flo[x.first][x.second].ft+1;
pill b=make_pair(nx,ny);
if (!vis[nx][ny])
v.push(b);
vis[nx][ny]=1;
}
}
}
int bfs(person x)
{
memset(vis,0,sizeof vis);
while (!q.empty()) q.pop();
q.push(x);
int s=1<<30;
while (!q.empty()){
person u=q.front();
q.pop();
if (u.t>=s) continue;
if (u.x==0 || u.y==0 || u.x==R-1 || u.y==C-1) {s=u.t;break;}
for (int i=0;i<4;i++){
int xx=u.x+dir[i][0];
int yy=u.y+dir[i][1];
if (xx<0 || yy<0 || xx>=R || yy>=C)  continue;
if (xx==u.fx && yy==u.fy) continue;
if (flo[xx][yy].sta!=1 || flo[xx][yy].ft>=0 && flo[xx][yy].ft<=u.t+1) continue;
person b=(person){xx,yy,u.t+1,u.x,u.y};
if (!vis[xx][yy]) q.push(b);
vis[xx][yy]=1;
}
}
return s;
}
int main()
{
int t,sx,sy;char ch;
scanf("%d",&t);
while (t--){
while (!v.empty()) v.pop();
scanf("%d%d",&R,&C);
getchar();
for (int i=0;i<R;i++){
for (int j=0;j<C;j++){
scanf("%c",&ch);
//cout<<ch<<endl;
if (ch=='.') {flo[i][j].sta=1;flo[i][j].ft=-1;}
else if (ch=='#'){flo[i][j].sta=0;flo[i][j].ft=-1;}
else if (ch=='F'){
flo[i][j].sta=flo[i][j].ft=0;
pill a;a.first=i;a.second=j;v.push(a);
}
else if (ch=='J') sx=i,sy=j;
}
getchar();
}
init();
person a=(person){sx,sy,0,-1,-1};
int ans=bfs(a);
if (ans<(1<<30)) printf("%d\n",ans+1);
else  puts("IMPOSSIBLE");
}
return 0;
}

#include <iostream>
#include <cstdio>
#include <cstring>
#include <queue>
using namespace std;
int R,C;
int vis[30][30][5][5];
int mat[30][30];
int sx,sy,ex,ey;
int dir[][2]={{-1,0},{0,1},{1,0},{0,-1}};
struct t1{
int x,y,d,c,t;
};
int bfs(t1 a)
{
queue<t1> q;
q.push(a);
memset(vis,0,sizeof vis);
while (!q.empty()){
t1 u=q.front();
q.pop();
if (u.x==ex && u.y==ey && u.c==0){
//cout<<" pass "<<u.x<<" "<<u.y<<endl;
return u.t;
}
vis[u.x][u.y][u.d][u.c]=1;
int nd=u.d+1;
if (nd>3) nd=0;
t1 nx=u;
nx.d=nd;
nx.t=u.t+1;
if (!vis[nx.x][nx.y][nx.d][nx.c]) q.push(nx);
vis[nx.x][nx.y][nx.d][nx.c]=1;
nd=u.d-1;
if (nd<0) nd=3;
nx=u; nx.d=nd; nx.t=u.t+1;
if (!vis[nx.x][nx.y][nx.d][nx.c]) q.push(nx);
vis[nx.x][nx.y][nx.d][nx.c]=1;
int xx=u.x+dir[u.d][0];
int yy=u.y+dir[u.d][1];
if (xx<0 || yy<0 || xx>=R || yy>=C) continue;
if (mat[xx][yy]==0) continue;
int nc=u.c+1;
if (nc>4) nc=0;
t1 b=(t1){xx,yy,u.d,nc,u.t+1};
if (!vis[b.x][b.y][b.d][b.c]) q.push(b);
vis[b.x][b.y][b.d][b.c]=1;
}
return -1;
}
int main()
{
char ch;
int kase=0;
while (scanf("%d%d",&R,&C)){
if (R==0) break;
getchar();
memset(mat,0,sizeof mat);
for (int i=0;i<R;i++){
for (int j=0;j<C;j++){
ch=getchar();
if (ch!='#') mat[i][j]=1;
if (ch=='S') sx=i,sy=j;
if (ch=='T') ex=i,ey=j;
}
getchar();
}
//cout<<ex<<" exy "<<ey<<endl;
t1 a=(t1){sx,sy,0,0,0};
int ans=bfs(a);
if (kase) puts("");
printf("Case #%d\n",++kase);
if (ans==-1)puts("destination not reachable");
else printf("minimum time = %d sec\n",ans);
}
return 0;
}