题解：
我脑子里都是翔？？？
bfs一下就行了 我居然还想什么kd tree！真是too naive，，，
1 #include<cstdio> 2 3 #include<cstdlib> 4 5 #include<cmath> 6 7 #include<cstring> 8 9 #include<algorithm> 10 11 #include<iostream> 12 13 #include<vector> 14 15 #include<map> 16 17 #include<set> 18 19 #include<queue> 20 21 #include<string> 22 23 #define inf 1000000000 24 25 #define maxn 1000+5 26 27 #define maxm 200000+5 28 29 #define eps 1e-10 30 31 #define ll long long 32 33 #define pa pair<int,int> 34 35 #define for0(i,n) for(int i=0;i<=(n);i++) 36 37 #define for1(i,n) for(int i=1;i<=(n);i++) 38 39 #define for2(i,x,y) for(int i=(x);i<=(y);i++) 40 41 #define for3(i,x,y) for(int i=(x);i>=(y);i--) 42 43 #define for4(i,x) for(int i=head[x],y=e[i].go;i;i=e[i].next,y=e[i].go) 44 45 #define for5(n,m) for(int i=1;i<=n;i++)for(int j=1;j<=m;j++) 46 47 #define mod 1000000007 48 49 using namespace std; 50 51 inline int read() 52 53 { 54 55 int x=0,f=1;char ch=getchar(); 56 57 while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();} 58 59 while(ch>='0'&&ch<='9'){x=10*x+ch-'0';ch=getchar();} 60 61 return x*f; 62 63 } 64 int n,m,d[maxn][maxn]; 65 queue<pa>q; 66 bool v[maxn][maxn]; 67 const int dx[4]={0,1,-1,0}; 68 const int dy[4]={1,0,0,-1}; 69 70 int main() 71 72 { 73 74 freopen("input.txt","r",stdin); 75 76 freopen("output.txt","w",stdout); 77 78 n=read();m=read(); 79 for5(n,m)d[i][j]=inf; 80 for5(n,m) 81 { 82 char ch=getchar(); 83 while(ch!='0'&&ch!='1')ch=getchar(); 84 if(ch=='1'){d[i][j]=0;q.push(pa(i,j));} 85 } 86 while(!q.empty()) 87 { 88 int x=q.front().first,y=q.front().second;q.pop(); 89 for0(i,3) 90 { 91 int xx=x+dx[i],yy=y+dy[i]; 92 if(xx<1||xx>n||yy<1||yy>m||d[xx][yy]<=d[x][y])continue; 93 d[xx][yy]=d[x][y]+1; 94 if(!v[xx][yy]){v[xx][yy]=1;q.push(pa(xx,yy));} 95 } 96 } 97 for1(i,n){for1(j,m)printf("%d ",d[i][j]);printf("\n");} 98 99 return 0; 100 101 }