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=0;
    while(!isdigit(c)) c=getchar();
    while(isdigit(c)) x=(x<<3)+(x<<1)+(c^48),c=getchar();
}
#define N 702
const int d1[8]={0,1,0,-1,1,1,-1,-1};
const int d2[8]={1,0,-1,0,1,-1,1,-1};
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]=1; int p=1;
    while(!h.empty()){
        data u=h.front(); h.pop();
        for(int i=0;i<8;++i){
            int r1=u.x+d1[i],r2=u.y+d2[i];
            if(r1<1||r1>n||r2<1||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]=1;
        }
    }ans+=p;
}
int main(){
    read(n);read(m);
    for(re int i=1;i<=n;++i)
        for(re int j=1;j<=m;++j)
            read(H[i][j]);
    for(re int i=1;i<=n;++i)
        for(re int j=1;j<=m;++j)
            if(!vis[i][j]) bfs(i,j);
    printf("%d",ans);
    return 0;
}