bzoj1619 / P2919 [USACO08NOV]守护农场Guarding the Farm

P2919 [USACO08NOV]守护农场Guarding the Farm

相似题：P3456 [POI2007]GRZ-Ridges and Valleys

按海拔是否相同分块

每次bfs海拔相同的块，根据与周围的块的大小关系判断是否是山丘。

 #include<iostream>
 #include<cstdio>
 #include<cstring>
 #include<queue>
 #include<cctype>
 #define re register
 using namespace std;
 void read(int &x){
     char c=getchar();x=;
     while(!isdigit(c)) c=getchar();
     while(isdigit(c)) x=(x<<)+(x<<)+(c^),c=getchar();
 }
 #define N 702
 const int d1[]={,,,-,,,-,-};
 const int d2[]={,,-,,,-,,-};
 struct data{int x,y;};
 int n,m,H[N][N],ans; bool vis[N][N];
 void bfs(int f1,int f2){
     queue <data> h; h.push((data){f1,f2});
     vis[f1][f2]=; int p=;
     while(!h.empty()){
         data u=h.front(); h.pop();
         for(int i=;i<;++i){
             int r1=u.x+d1[i],r2=u.y+d2[i];
             if(r1<||r1>n||r2<||r2>m) continue;
             p&=(H[r1][r2]<=H[u.x][u.y]);//是否是山丘
             if(vis[r1][r2]) continue;
             if(H[r1][r2]==H[u.x][u.y])
                 h.push((data){r1,r2}),vis[r1][r2]=;
         }
     }ans+=p;
 }
 int main(){
     read(n);read(m);
     for(re int i=;i<=n;++i)
         for(re int j=;j<=m;++j)
             read(H[i][j]);
     for(re int i=;i<=n;++i)
         for(re int j=;j<=m;++j)
             if(!vis[i][j]) bfs(i,j);
     printf("%d",ans);
     return ;
 }