bzoj2547

题解：

二分+宽搜+KM

显然答案不能太大

然后二分一下

代码:

#include<bits/stdc++.h>
const int N=,M=;
using namespace std;
const int dx[]={-,,,},dy[]={,,-,};
int m,n,cnt,pt,tot,c[N][N],d[N][N],x,y,t,path[N],bo[N],inq[N][N],mp[N][N];
struct node{int x,y;}a[N],b[N],h[N+];
void bfs(int sx,int sy,int p)
{
    memset(d,0x3f,sizeof(d));
    d[sx][sy]=;
    int i,t,head=,tail=;
    node u,v;
    h[].x=sx;h[].y=sy;
    memset(inq,,sizeof(inq));
    while (head!=tail)
     {
        head=head%M+;u=h[head];inq[u.x][u.y]=;
        for (int i=;i<;i++)
         {
            v.x=u.x+dx[i];v.y=u.y+dy[i];
            if (v.x<=||v.x>m||v.y<=||v.y>n) continue;
            if (p^(d[u.x][u.y]&))
             if (c[v.x][v.y]<=c[u.x][u.y]) t=;else t=;
            else
             if (c[v.x][v.y]>=c[u.x][u.y]) t=;else t=;
            if (d[u.x][u.y]+t<d[v.x][v.y])
             {
                d[v.x][v.y]=d[u.x][u.y]+t;
                if (!inq[v.x][v.y]){inq[v.x][v.y]=;tail=tail%M+;h[tail]=v;}
             }
        }
    }
}
int dfs(int x,int lim)
{
    for (int i=;i<=tot;i++)
     if (bo[i]&&mp[x][i]<=lim)
      {
        bo[i]=;
        if (!path[i]||dfs(path[i],lim))
         {
            path[i]=x;
            return ;
         }
      }
    return ;
}
int pd(int x)
{
    int tmp=;
    memset(path,,sizeof(path));
    for (int i=;i<=(cnt<<);i++)
     {
        memset(bo,,sizeof(bo));
        tmp+=(dfs(i,x));
     }
    return tmp+x>=(cnt<<);
}
int main()
{
    scanf("%d%d%d%d",&m,&n,&cnt,&pt);
    for (int i=;i<=(cnt<<|);i++)scanf("%d%d",&a[i].x,&a[i].y);
    for (int i=;i<=pt;i++)
     {
        scanf("%d%d%d",&x,&y,&t);
        while (t--){b[++tot].x=x;b[tot].y=y;}
    }
    for (int i=;i<=m;i++)
     for (int j=;j<=n;j++)scanf("%d",&c[i][j]);
    for (int i=;i<=(cnt<<);i++)
     {
        if (i<=cnt) bfs(a[i].x,a[i].y,); else bfs(a[i].x,a[i].y,);
        for (int j=;j<=tot;j++) mp[i][j]=d[b[j].x][b[j].y];
    }
    int l=,r=cnt<<;
    while (l<r)
     {
        int mid=(l+r)>>;
        if (pd(mid)) r=mid;
        else l=mid+;
     }
    printf("%d\n",l);
    return ;
}