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1 #include<cstdio> 2 #include<iostream> 3 #include<cmath> 4 #include<cstring> 5 #include<algorithm> 6 #define maxn 100005 7 #define eps 1E-9 8 #define inf 1E100 9 using namespace std; 10 int n,flag,cnt,siz,pos[maxn]; 11 double w[maxn],d[maxn],dist[maxn],tot,tmp,ans,t1,t2,t3,val[maxn]; 12 double a,b,l,r,f[maxn],p[maxn]; 13 struct Line{ 14 double k,b; 15 int id; 16 }line[maxn],tl[maxn]; 17 bool cmp(Line x,Line y){ 18 if (abs(x.k-y.k)>eps) return x.k>y.k; 19 return x.b<y.b; 20 } 21 double calc(Line l1,Line l2){return -(l1.b-l2.b)/(l1.k-l2.k);} 22 struct DATA{ 23 double x; 24 int id; 25 }list[maxn]; 26 void solve(){ 27 memcpy(tl,line,sizeof(line)); 28 sort(tl+1,tl+n+1,cmp); 29 for (int i=1,j,t;i<=n;i=j){ 30 line[++cnt]=tl[i],t=0; 31 for (j=i;tl[j].k==tl[i].k;j++) if (tl[j].b==tl[i].b) pos[tl[j].id]=cnt,t++; 32 for (j=i;tl[j].k==tl[i].k;j++) if (tl[j].b==tl[i].b) p[tl[j].id]=1.0/t; 33 } 34 list[siz=1]=(DATA){-inf,1}; 35 for (int i=2;i<=cnt;i++){ 36 double t=calc(line[i],line[list[siz].id]); 37 while (t<list[siz].x) siz--,t=calc(line[i],line[list[siz].id]); 38 list[++siz]=(DATA){t,i}; 39 } 40 list[++siz]=(DATA){inf,cnt+1}; 41 l=a,r=b,flag=0; 42 for (int i=1;i<=siz&&flag!=2;i++){ 43 if (list[i].x>l){ 44 if (!flag) flag=1,f[list[i-1].id]=(list[i].x-l)/(r-l); 45 else if (flag==1&&list[i].x<r) f[list[i-1].id]=(list[i].x-list[i-1].x)/(r-l); 46 else if (list[i].x>=r) f[list[i-1].id]=(r-list[i-1].x)/(r-l),flag=2; 47 } 48 } 49 for (int i=1;i<=n;i++) p[i]=f[pos[i]]*p[i]; 50 for (int i=1;i<=n;i++) printf("%.3lf\n",p[i]); 51 } 52 int main(){ 53 scanf("%d%lf%lf",&n,&a,&b); 54 for (int i=1;i<n;i++) scanf("%lf",&w[i]); 55 for (int i=1;i<=n;i++) scanf("%lf",&d[i]); 56 for (int i=1;i<=n;i++) dist[i]=d[i]; 57 for (int i=1;i<=n;i++) dist[i]+=dist[i-1]; 58 tot=dist[n]; 59 if (a==b){ 60 w[n]=a; 61 t1=w[1]*tot,t3=w[1]; 62 for (int i=2;i<=n;i++){ 63 tmp+=w[i]*(dist[i]-dist[1])*(tot-dist[i]+dist[1]); 64 t1+=w[i]*(dist[i]-dist[1]); 65 t2+=w[i]*(tot-dist[i]+dist[1]); 66 t3+=w[i]; 67 } 68 val[1]=ans=tmp; 69 for (int i=2;i<=n;i++){ 70 tmp+=t1*d[i]-t2*d[i]-t3*d[i]*d[i]; 71 ans=min(ans,tmp); 72 val[i]=tmp; 73 t1+=w[i]*tot,t2-=w[i]*tot; 74 t1-=t3*d[i],t2+=t3*d[i]; 75 } 76 cnt=0; 77 for (int i=1;i<=n;i++) if (abs(val[i]-ans)<=eps) cnt++; 78 for (int i=1;i<=n;i++) if (abs(val[i]-ans)<=eps) printf("%.3lf\n",1.0/cnt); 79 else puts("0.000"); 80 return 0; 81 } 82 l=0,r=tot; 83 for (int i=1;i<=n;i++) l+=d[i],r-=d[i],line[i].k=l*r; 84 t1=w[1]*tot,t3=w[1]; 85 for (int i=2;i<=n;i++){ 86 tmp+=w[i]*(dist[i]-dist[1])*(tot-dist[i]+dist[1]); 87 t1+=w[i]*(dist[i]-dist[1]); 88 t2+=w[i]*(tot-dist[i]+dist[1]); 89 t3+=w[i]; 90 } 91 line[1].b=tmp; 92 for (int i=2;i<=n;i++){ 93 tmp+=t1*d[i]-t2*d[i]-t3*d[i]*d[i]; 94 line[i].b=tmp; 95 t1+=w[i]*tot,t2-=w[i]*tot; 96 t1-=t3*d[i],t2+=t3*d[i]; 97 } 98 for (int i=1;i<=n;i++) line[i].id=i; 99 solve(); 100 return 0; 101 }
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原文地址：http://www.cnblogs.com/chenyushuo/p/4922369.html
