HK 2016(Peak Tower-矩形面积并)

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在W∗H(m2)的方框里，由n个矩形（坐标平行于坐标轴），每个矩形开始在(sx,sy)，且以(vx,vy)的速度匀速移动。问在0~Es的时间里，方框内被矩形覆盖的最小面积。
矩形面积并，处理出若干个关键时间点（线线相撞的时刻）。
#include<bits/stdc++.h> using namespace std;#define For(i,n) for(int i=1;i<=n;i++)#define Fork(i,k,n) for(int i=k;i<=n;i++)#define ForkD(i,k,n) for(int i=n;i>=k;i--)#define Rep(i,n) for(int i=0;i<n;i++)#define ForD(i,n) for(int i=n;i;i--)#define RepD(i,n) for(int i=n;i>=0;i--)#define Forp(x) for(int p=pre[x];p;p=next[p])#define Forpiter(x) for(int &p=iter[x];p;p=next[p])  #define Lson (o<<1)#define Rson ((o<<1)+1)#define MEM(a) memset(a,0,sizeof(a));#define MEMI(a) memset(a,0x3f,sizeof(a));#define MEMi(a) memset(a,128,sizeof(a));#define MEMx(a,b) memset(a,b,sizeof(a));#define INF (0x3f3f3f3f)#define F (1000000007)#define pb push_back#define mp make_pair#define fi first#define se second#define vi vector<int> #define pi pair<int,int>#define SI(a) ((a).size())#define Pr(kcase,ans) printf("Case #%d: %lld\n",kcase,ans);#define PRi(a,n) For(i,n-1) cout<<a[i]<<' '; cout<<a[n]<<endl;#define PRi2D(a,n,m) For(i,n) { \                        For(j,m-1) cout<<a[i][j]<<' ';\                        cout<<a[i][m]<<endl; \                        } #pragma comment(linker, "/STACK:102400000,102400000")#define ALL(x) (x).begin(),(x).end()#define gmax(a,b) a=max(a,b);#define gmin(a,b) a=min(a,b);typedef long long ll;typedef long double ld;typedef unsigned long long ull;ll mul(ll a,ll b){return (a*b)%F;}ll add(ll a,ll b){return (a+b)%F;}ll sub(ll a,ll b){return ((a-b)%F+F)%F;}void upd(ll &a,ll b){a=(a%F+b%F)%F;}inline int read(){    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;} #define MAXN (2000)int n;double W,H,E,w[MAXN],h[MAXN],sx[MAXN],vx[MAXN],sy[MAXN],vy[MAXN];const double eps = 1e-8;vector<double> v;//si+vit==sj+vjt si-sj=(vj-vi)tvoid pre(int n) {    v.pb(0);    For(i,n) {        Fork(j,i+1,n) {            if (fabs(vx[j]-vx[i])>eps) {                double tt=(sx[i]-sx[j])/(vx[j]-vx[i]);                if (tt>0 && tt<E) v.pb(tt);            }            if (fabs(vy[j]-vy[i])>eps) {                double tt=(sy[i]-sy[j])/(vy[j]-vy[i]);                if (tt>0 && tt<E) v.pb(tt);            }        }    }    v.pb(E);}namespace RectUnion{    struct data    {        double x1,x2,y;        int flag;        }a[3000];    double hash[3000];    double sum[3000];    int col[3000];    inline bool cp(data a,data b){return a.y<b.y;}    void pushup(int size,int l,int r)    {        if(col[size])sum[size]=hash[r+1]-hash[l];        else if(l==r)sum[size]=0;        else sum[size]=sum[size*2]+sum[size*2+1];    }    void update(int L,int R,int flag,int l,int r,int size)    {        if(L<=l&&R>=r)        {            col[size]+=flag;            pushup(size,l,r);            return;        }        int m=(l+r)/2;        if(L<=m)update(L,R,flag,l,m,size*2);        if(R>m)update(L,R,flag,m+1,r,size*2+1);        pushup(size,l,r);    }    double work(double t,int n) {        double x1,y1,x2,y2;        int cnt=0;        for(int i=1;i<=n;i++)        {            x1=sx[i]+ t* vx[i];            y1=sy[i]+ t* vy[i];            x2=x1+w[i];            y2=y1+h[i];            x1=max(x1,0.),x2=min(x2,W);            x2=max(x2,0.),x1=min(x1,W);            y1=max(y1,0.),y2=min(y2,H);            y2=max(y2,0.),y1=min(y1,H);            if(x1>=x2 || y1>=y2) continue;            ++cnt;            a[2*cnt-1].x1=a[2*cnt].x1=x1;            a[2*cnt-1].x2=a[2*cnt].x2=x2;            a[2*cnt-1].y=y1;a[2*cnt].y=y2;            a[2*cnt-1].flag=1;a[2*cnt].flag=-1;            hash[2*cnt-1]=x1;hash[2*cnt]=x2;        }        sort(a+1,a+2*cnt+1,cp);sort(hash+1,hash+2*cnt+1);        memset(col,0,sizeof(col));        memset(sum,0,sizeof(sum));        double ans=0;        for(int i=1;i<=2*cnt;i++)        {            int l=lower_bound(hash+1,hash+2*cnt+1,a[i].x1)-hash;            int r=lower_bound(hash+1,hash+2*cnt+1,a[i].x2)-hash-1;            if(l<=r)update(l,r,a[i].flag,1,2*cnt,1);            ans+=sum[1]*(a[i+1].y-a[i].y);        }        return ans;        printf("%.2lf\n",ans);    }};int main(){//  freopen("C.in","r",stdin);//  freopen(".out","w",stdout);    n=read();    cin>>W>>H>>E;       For(i,n) {        cin>>w[i]>>h[i]>>sx[i]>>sy[i]>>vx[i]>>vy[i];    }    Fork(i,n+1,2*n) {        sx[i] = sx[i-n]+w[i-n];        vx[i] = vx[i-n];        sy[i] = sy[i-n]+h[i-n];        vy[i] = vy[i-n];    }    sx[n*2+1]=0,vx[n*2+1]=0;    sy[n*2+1]=0,vx[n*2+1]=0;    sx[n*2+2]=W,vy[n*2+2]=0;    sy[n*2+2]=H,vy[n*2+2]=0;    pre(n*2+2);    double ans=RectUnion::work(0,n);    sort(ALL(v));    for(double t:v) {        double p=RectUnion::work(t,n);        gmin(ans,p)    }    for(double t=0;t<=E;t+=0.01) {        double p=RectUnion::work(t,n);//      if (p<ans) cout<<t<<endl;//      cout<<t;        gmin(ans,p)    }    cout<<setiosflags(ios::fixed)<<setprecision(10)<<ans<<endl;    return 0;}
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