bzoj1644 / P1649 [USACO07OCT]障碍路线Obstacle Course

P1649 [USACO07OCT]障碍路线Obstacle Course

bfs

直接上个bfs

注意luogu的题目和bzoj有不同（bzoj保证有解，还有输入格式不同）。

 #include<iostream>
 #include<cstdio>
 #include<cstring>
 #include<queue>
 using namespace std;
 #define pi pair<int,int>
 #define mkp make_pair
 #define N 105
 const int d1[]={,,,-};
 const int d2[]={,,-,};
 char q[]; bool dan[N][N];
 int a[N][N],vis[N][N],n;
 pi S,T; queue<pi> h;
 int main(){
     scanf("%d",&n);
     for(int i=;i<=n;++i){
         for(int j=;j<=n;++j){
             scanf("%s",q);
             if(q[]=='A') S=mkp(i,j);
             if(q[]=='B') T=mkp(i,j);
             if(q[]=='x') dan[i][j]=;
         }
     }h.push(S);
     while(!h.empty()){
         pi u=h.front(); h.pop();
         for(int i=;i<;++i){
             int r1=u.first+d1[i],r2=u.second+d2[i];
             while(!dan[r1][r2]){
                 if(r1>n||r1<||r2>n||r2<) break;
                 if(vis[r1][r2]){
                     r1+=d1[i];r2+=d2[i];
                     continue;
                 }
                 vis[r1][r2]=vis[u.first][u.second]+;
                 if(mkp(r1,r2)==T){
                     printf("%d",max(,vis[r1][r2]-));
                     return ;
                 }h.push(mkp(r1,r2));
                 r1+=d1[i];r2+=d2[i];
             }
         }
     }printf("-1");
     return ;
 }

P1649

 #include<iostream>
 #include<cstdio>
 #include<cstring>
 #include<queue>
 using namespace std;
 #define pi pair<int,int>
 #define mkp make_pair
 #define N 105
 const int d1[]={,,,-};
 const int d2[]={,,-,};
 char q[N]; bool dan[N][N];
 int a[N][N],vis[N][N],n;
 pi S,T; queue<pi> h;
 int main(){
     scanf("%d",&n);
     for(int i=;i<=n;++i){
         scanf("%s",q);
         for(int j=;j<=n;++j){
             if(q[j-]=='A') S=mkp(i,j);
             if(q[j-]=='B') T=mkp(i,j);
             if(q[j-]=='x') dan[i][j]=;
         }
     }h.push(S);
     while(!h.empty()){
         pi u=h.front(); h.pop();
         for(int i=;i<;++i){
             int r1=u.first+d1[i],r2=u.second+d2[i];
             while(!dan[r1][r2]){
                 if(r1>n||r1<||r2>n||r2<) break;
                 if(vis[r1][r2]){
                     r1+=d1[i];r2+=d2[i];
                     continue;
                 }vis[r1][r2]=vis[u.first][u.second]+;
                 if(mkp(r1,r2)==T){
                     printf("%d",max(,vis[r1][r2]-));
                     return ;
                 }h.push(mkp(r1,r2));
                 r1+=d1[i];r2+=d2[i];
             }
         }
     }
 }

bzoj1644