AC日记——[SDOI2017]相关分析 洛谷 P3707
思路：
裸线段树；
（玄学ac）；
代码：
#include <bits/stdc++.h> using namespace std; #define maxn 100005 struct TreeNodeType { int l,r,mid; double flagx2,flagy2,flagx3,flagy3,size; double sumx,sumy,suml,sumxy,sumx2,sumy2,suml2; bool if_3; inline void updata2(double posx,double posy) { sumx2+=size*posx*posx+2*posx*sumx; sumy2+=size*posy*posy+2*posy*sumy; sumxy+=size*posx*posy+sumx*posy+sumy*posx; sumx+=size*posx,sumy+=size*posy; flagx2+=posx,flagy2+=posy; } inline void updata3(double posx,double posy) { sumxy=size*posx*posy+suml*(posx+posy)+suml2; sumx2=size*posx*posx+posx*2*suml+suml2; sumy2=size*posy*posy+posy*2*suml+suml2; sumx=size*posx+suml,sumy=size*posy+suml; if_3=true,flagx3=posx,flagy3=posy; flagx2=0,flagy2=0; } }; struct TreeNodeType tree[maxn<<2]; int n,m; double Sumx,Sumy,Sumx2,Sumy2,Sumxy,ai[maxn],bi[maxn]; inline void updata(int now) { tree[now].sumx=tree[now<<1].sumx+tree[now<<1|1].sumx; tree[now].sumy=tree[now<<1].sumy+tree[now<<1|1].sumy; tree[now].suml=tree[now<<1].suml+tree[now<<1|1].suml; tree[now].sumxy=tree[now<<1].sumxy+tree[now<<1|1].sumxy; tree[now].sumx2=tree[now<<1].sumx2+tree[now<<1|1].sumx2; tree[now].sumy2=tree[now<<1].sumy2+tree[now<<1|1].sumy2; tree[now].suml2=tree[now<<1].suml2+tree[now<<1|1].suml2; } void build(int now,int l,int r) { tree[now].l=l,tree[now].r=r,tree[now].size=r-l+1; if(l==r) { tree[now].sumx=ai[l],tree[now].sumy=bi[l],tree[now].suml=l; tree[now].sumxy=ai[l]*bi[l],tree[now].suml2=(double)l*l; tree[now].sumx2=ai[l]*ai[l],tree[now].sumy2=bi[l]*bi[l]; return; } tree[now].mid=l+r>>1; build(now<<1,l,tree[now].mid); build(now<<1|1,tree[now].mid+1,r); updata(now); } inline void pushdown(int now) { if(tree[now].if_3) { tree[now].if_3=false; tree[now<<1].updata3(tree[now].flagx3,tree[now].flagy3); tree[now<<1|1].updata3(tree[now].flagx3,tree[now].flagy3); } if(tree[now].flagx2||tree[now].flagy2) { tree[now<<1].updata2(tree[now].flagx2,tree[now].flagy2); tree[now<<1|1].updata2(tree[now].flagx2,tree[now].flagy2); tree[now].flagx2=0,tree[now].flagy2=0; } } void operation1(int now,int l,int r) { if(tree[now].l>=l&&tree[now].r<=r) { Sumx+=tree[now].sumx,Sumy+=tree[now].sumy; Sumx2+=tree[now].sumx2,Sumy2+=tree[now].sumy2; Sumxy+=tree[now].sumxy;return; } if(tree[now].if_3||tree[now].flagx2||tree[now].flagy2) pushdown(now); if(l<=tree[now].mid) operation1(now<<1,l,r); if(r>tree[now].mid) operation1(now<<1|1,l,r); } void operation2(int now,int l,int r,double s,double t) { if(tree[now].l>=l&&tree[now].r<=r) { tree[now].updata2(s,t); return; } if(tree[now].if_3||tree[now].flagx2||tree[now].flagy2) pushdown(now); if(l<=tree[now].mid) operation2(now<<1,l,r,s,t); if(r>tree[now].mid) operation2(now<<1|1,l,r,s,t); updata(now); } void operation3(int now,int l,int r,double s,double t) { if(tree[now].l>=l&&tree[now].r<=r) { tree[now].updata3(s,t); return; } if(tree[now].if_3||tree[now].flagx2||tree[now].flagy2) pushdown(now); if(l<=tree[now].mid) operation3(now<<1,l,r,s,t); if(r>tree[now].mid) operation3(now<<1|1,l,r,s,t); updata(now); } int main() { scanf("%d%d",&n,&m); for(int i=1;i<=n;i++) scanf("%lf",&ai[i]); for(int i=1;i<=n;i++) scanf("%lf",&bi[i]); build(1,1,n); int op,l,r;double s,t; while(m--) { scanf("%d%d%d",&op,&l,&r); if(op==1) { Sumx=0,Sumy=0,Sumxy=0,Sumx2=0,Sumy2=0; operation1(1,l,r); double size=r-l+1,x_=Sumx/size,y_=Sumy/size; double a=Sumxy-Sumy*x_-Sumx*y_+y_*x_*size; double b=Sumx2-2*Sumx*x_+x_*x_*size; printf("%.10lf\n",a/b); } if(op==2) scanf("%lf%lf",&s,&t),operation2(1,l,r,s,t); if(op==3) scanf("%lf%lf",&s,&t),operation3(1,l,r,s,t); } return 0; }
