P4048 [JSOI2010]冷冻波

出题人你tm搞笑呢,冰霜新星翻成冷冻波,而且tm就只能打一只小精灵???巫妖王都想来砍死你

首先要搞出每个巫妖能不能打到每一个小精灵,然后二分时间,就能算出每个巫妖可以打的次数,网络流check即可

但是你要搞出每个巫妖能不能打到每一个小精灵。。。贼jb麻烦,为此搜了N个公式才搞出来,我还是太菜了

#include<bits/stdc++.h>
#define il inline
#define vd void
#define sqr(x) ((x)*(x))
typedef long long ll;
il int gi(){
    int x=0,f=1;
    char ch=getchar();
    while(!isdigit(ch)){
        if(ch=='-')f=-1;
        ch=getchar();
    }
    while(isdigit(ch))x=x*10+ch-'0',ch=getchar();
    return x*f;
}
bool yes[201][201];
int X0[201],Y0[201],R[201],d[201];
int X1[201],Y1[201],X2[201],Y2[201],r2[201];
const int maxn=410,S=401,T=402,maxm=500000;
int fir[maxn],head[maxn],dis[maxm],nxt[maxm],w[maxm],id,dep[maxn];
il vd link(int a,int b,int c){
    nxt[++id]=fir[a],fir[a]=id,dis[id]=b,w[id]=c;
    nxt[++id]=fir[b],fir[b]=id,dis[id]=a,w[id]=0;
}
il bool BFS(){
    static int que[maxn],hd,tl;
    memset(dep,0,sizeof dep);
    hd=tl=0;que[tl++]=S;
    dep[S]=1;
    while(hd^tl){
        int x=que[hd++];
        for(int i=fir[x];i;i=nxt[i])
            if(w[i]&&!dep[dis[i]])dep[dis[i]]=dep[x]+1,que[tl++]=dis[i];
    }
    return dep[T];
}
il int Dinic(int x,int maxflow){
    if(x==T)return maxflow;
    int ret=0;
    for(int&i=head[x];i;i=nxt[i])
        if(w[i]&&dep[dis[i]]==dep[x]+1){
            int d=Dinic(dis[i],std::min(w[i],maxflow-ret));
            w[i]-=d,w[i^1]+=d,ret+=d;
            if(ret==maxflow)break;
        }
    return ret;
}
int main(){
#ifndef ONLINE_JUDGE
    freopen("4048.in","r",stdin);
    freopen("4048.out","w",stdout);
#endif
    int n=gi(),m=gi(),t=gi();
    for(int i=1;i<=n;++i)X0[i]=gi(),Y0[i]=gi(),R[i]=gi(),d[i]=gi();
    for(int i=1;i<=m;++i)X1[i]=gi(),Y1[i]=gi();
    for(int i=1;i<=t;++i)X2[i]=gi(),Y2[i]=gi(),r2[i]=gi();
    for(int i=1;i<=n;++i)
        for(int j=1;j<=m;++j)
            if(sqr(X0[i]-X1[j])+sqr(Y0[i]-Y1[j])<=R[i]*R[i]){
                bool flg=1;
                for(int k=1;k<=t;++k)
                    if(X0[i]==X1[j]){
                        if(abs(X0[i]-X2[k])>r2[k])continue;
                        double yy0=Y0[i],yy1=Y1[j];
                        if(yy0>yy1)std::swap(yy0,yy1);
                        if(yy0<=Y2[k]&&Y2[k]<=yy1){flg=0;break;}
                    }else{
                        double k0=1.0*(Y0[i]-Y1[j])/(X0[i]-X1[j]),b0=Y0[i]-X0[i]*k0;
                        double dist1=fabs(k0*X2[k]-Y2[k]+b0)/sqrt(1+k0*k0);
                        double xx=X2[k]+sin(atan(-1/k)),xx0=X0[i],xx1=X1[j];
                        if(xx0>xx1)std::swap(xx0,xx1);
                        if(dist1<=r2[k]&&xx0<=xx&&xx<=xx1){flg=0;break;}
                    }
                if(flg)yes[i][j]=1;
            }
    for(int i=1;i<=m;++i){
        for(int j=1;j<=n;++j)if(yes[j][i])goto GG;
        return puts("-1"),0;
      GG:;
    }
    int l=0,r=20000*m,mid;
    while(l<r){
        mid=((l+r)>>1);
        memset(fir,0,sizeof fir);id=1;
        for(int i=1;i<=n;++i)link(S,i,mid/d[i]+1);
        for(int i=1;i<=m;++i)link(i+n,T,1);
        for(int i=1;i<=n;++i)
            for(int j=1;j<=m;++j)
                if(yes[i][j])link(i,j+n,1);
        int tot=0;while(BFS())memcpy(head,fir,sizeof head),tot+=Dinic(S,1e9);
        if(tot==m)r=mid;
        else l=mid+1;
    }
    printf("%d\n",l);
    return 0;
}

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转载自www.cnblogs.com/xzz_233/p/9819285.html