[BZOJ4541][HNOI2016]矿区(平面图转对偶图)

https://www.cnblogs.com/ljh2000-jump/p/6423399.html

 #include<cmath>
 #include<vector>
 #include<cstdio>
 #include<algorithm>
 #define rep(i,l,r) for (int i=(l); i<=(r); i++)
 typedef long long ll;
 using namespace std;

 const int N=;
 int n,m,Q,x,y,d,cnt=,nxt[N],tot,rt,bel[N],fa[N],ask[N];
 bool vis[N],in[N];
 ll s[N],sp[N],fz,fm;

 struct P{ int x,y; }p[N];
 P operator -(const P &a,const P &b){ return (P){a.x-b.x,a.y-b.y}; }
 ll operator *(const P &a,const P &b){ return 1ll*a.x*b.y-1ll*b.x*a.y; }

 struct E{
     int u,v,id; double sl;
     E(){}; E(int a,int b,int i):u(a),v(b),id(i),sl(atan2(p[b].y-p[a].y,p[b].x-p[a].x)){}
 }e[N];
 bool operator <(const E &a,const E &b){ return a.sl<b.sl; }
 vector<E>w[N],tr[N];
 void add(int u,int v){ cnt++; e[cnt]=(E){u,v,cnt}; w[u].push_back(e[cnt]); }

 ll gcd(ll a,ll b){ return b ? gcd(b,a%b) : a; }

 int find(int x,E b){
     int l=,r=w[x].size()-;
     while (l<r){
         int mid=(l+r+)>>;
         if (b<w[x][mid]) r=mid-; else l=mid;
     }
     return l;
 }

 void dfs(int x){
     vis[x]=; sp[x]=s[x]*s[x]; s[x]<<=; int ed=tr[x].size()-;
     rep(i,,ed){
         int v=tr[x][i].v; if (vis[v]) continue;
         fa[v]=x; in[tr[x][i].id]=in[tr[x][i].id^]=;
         dfs(v); s[x]+=s[v]; sp[x]+=sp[v];
     }
 }

 int main(){
     freopen("bzoj4541.in","r",stdin);
     freopen("bzoj4541.out","w",stdout);
     scanf("%d%d%d",&n,&m,&Q);
     rep(i,,n) scanf("%d%d",&x,&y),p[i]=(P){x,y};
     rep(i,,m) scanf("%d%d",&x,&y),add(x,y),add(y,x);
     rep(i,,n) sort(w[i].begin(),w[i].end());
     rep(i,,cnt){
         int ne=find(e[i].v,e[i^])-;
         if (ne==-) ne=w[e[i].v].size()-;
         nxt[i]=w[e[i].v][ne].id;
     }
     rep(i,,cnt) if (!bel[i]){
         bel[i]=bel[nxt[i]]=++tot;
         for (int x=nxt[i]; e[x].v!=e[i].u; x=nxt[x],bel[x]=tot)
             s[tot]+=(p[e[x].u]-p[e[i].u])*(p[e[x].v]-p[e[i].u]);
         if (s[tot]<=) rt=tot;
     }
     rep(i,,cnt) tr[bel[i]].push_back(E(bel[i],bel[i^],i));
     dfs(rt);
     while (Q--){
         scanf("%d",&d); d=(d+fz)%n+;
         rep(i,,d) scanf("%d",&ask[i]),ask[i]=(ask[i]+fz)%n+;
         ask[d+]=ask[]; fz=fm=;
         rep(i,,d){
             int x=w[ask[i]][find(ask[i],E(ask[i],ask[i+],))].id;
             if (!in[x]) continue;
             if (fa[bel[x]]==bel[x^]) fm+=s[bel[x]],fz+=sp[bel[x]];
                 else fm-=s[bel[x^]],fz-=sp[bel[x^]];
         }
         ll d=gcd(fz,fm); fz/=d; fm/=d; printf("%lld %lld\n",fz,fm);
     }
     return ;
 }