bzoj1901: Zju2112 Dynamic Rankings 主席树+树状数组

主席树+树状数组求带修改的区间第k大

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#include<bits/stdc++.h> using namespace std; int n,m,root[200100],q1[100000],q2[100000],tot=0,dd,len=0,a[100010],hash[200010],sum[5001000],l[5010000],r[5010000],b[1000100],c[1000010],d[1000010]; char s[10010]; int lowbit(int pp) {return pp&(-pp);} void update(int &rt,int L,int R,int x,int val) {     if(!rt)rt=++len;     sum[rt]+=val;     if(L<R)     {         int mid=(L+R)>>1;         if(x<=mid)update(l[rt],L,mid,x,val);         else update(r[rt],mid+1,R,x,val);     } } int main() {     //freopen("xf.in","r",stdin);     //freopen("xf.out","w",stdout);     scanf("%d%d",&n,&m);     for(int i=1;i<=n;i++)     {         scanf("%d",&a[i]);         hash[++tot]=a[i];     }     for(int i=1;i<=m;i++)     {         cin>>s[i];         if(s[i]=='Q')scanf("%d%d%d",&b[i],&c[i],&d[i]);         else {scanf("%d%d",&b[i],&c[i]);hash[++tot]=c[i];}     }     sort(hash+1,hash+tot+1);     dd=unique(hash+1,hash+tot+1)-hash-1;     for(int i=1;i<=n;i++)     {         int x=lower_bound(hash+1,hash+dd+1,a[i])-hash;         for(int j=i;j<=n;j+=lowbit(j))update(root[j],1,dd,x,1);     }     for(int i=1;i<=m;i++)     {         if(s[i]=='Q')         {             int xx=b[i]-1,yy=c[i],L=1,R=dd;             int x=d[i];             int tail1=0,tail2=0;             while(xx)                 {                     q1[++tail1]=root[xx];xx-=lowbit(xx);                 }                 while(yy)                 {                     q2[++tail2]=root[yy];yy-=lowbit(yy);                 }             while(L<R)             {                                    int ans=0;                 for(int j=1;j<=tail1;j++)ans-=sum[l[q1[j]]];                 for(int j=1;j<=tail2;j++)ans+=sum[l[q2[j]]];                 int mid=(L+R)>>1;                 if(x<=ans)                 {                     R=mid;                                            for(int j=1;j<=tail1;j++)                         q1[j]=l[q1[j]];                     for(int j=1;j<=tail2;j++)                         q2[j]=l[q2[j]];                 }                 else                 {                     L=mid+1;                     x-=ans;                     for(int j=1;j<=tail1;j++)                         q1[j]=r[q1[j]];                     for(int j=1;j<=tail2;j++)                         q2[j]=r[q2[j]];                 }             }             printf("%d\n",hash[L]);         }         else         {             int x=lower_bound(hash+1,hash+dd+1,a[b[i]])-hash;             for(int j=b[i];j<=n;j+=lowbit(j))update(root[j],1,dd,x,-1);             x=lower_bound(hash+1,hash+dd+1,c[i])-hash;             for(int j=b[i];j<=n;j+=lowbit(j))update(root[j],1,dd,x,1);             a[b[i]]=c[i];         }     }     return 0; }