【wikioi1227】 方格取数 2

#include<cstdio>#include<cstring>#include<iostream>#define INF 0x7fffffff #define N 6001#define M 1000010using namespace std;struct data{int from,to,v,c,next;}e[M];long long ans;int n,k,dis[N],head[N],from[N],q[M],cnt=1;bool inq[N];void insert(int u,int v,int w,int c){e[++cnt].from=u;e[cnt].to=v;e[cnt].v=w;e[cnt].c=c;e[cnt].next=head[u];head[u]=cnt;}void ins(int u,int v,int w,int c){insert(u,v,w,c);insert(v,u,0,-c);}bool spfa(){int t=0,w=1,i,now;memset(dis,-1,sizeof(dis));q[0]=0;inq[0]=1;dis[0]=0;while(t<w){now=q[t++];i=head[now];while(i){if(e[i].v>0&&dis[now]+e[i].c>dis[e[i].to]){dis[e[i].to]=dis[now]+e[i].c;from[e[i].to]=i;if(!inq[e[i].to]){q[w++]=e[i].to;inq[e[i].to]=true;}}i=e[i].next;inq[now]=false;}}if(dis[6000]==-1)return false;else return true;}void mincf(){int i=from[6000],sum=INF;while(i){sum=min(sum,e[i].v);i=from[e[i].from];}i=from[6000];while(i){e[i].v-=sum;e[i^1].v+=sum;ans+=sum*e[i].c;i=from[e[i].from];}}int main(){scanf("%d %d",&n,&k);for(int i=1;i<=n;i++)for(int j=1;j<=n;j++){int x;scanf("%d",&x);ins((i-1)*n+j,(i-1)*n+j+n*n,1,x);ins((i-1)*n+j,(i-1)*n+j+n*n,k,0);if(j<n)ins((i-1)*n+j+n*n,(i-1)*n+j+1,k,0);if(i<n)ins((i-1)*n+j+n*n,i*n+j,k,0);}ins(0,1,k,0);ins(2*n*n,6000,k,0);while(spfa())mincf();printf("%lld",ans);return 0;}