【带修改的主席树】BZOJ1901-Dynamic Rankings

稍后整理笔记。这题数据范围好像有点问题？

 #include<iostream>
 #include<cstdio>
 #include<cstring>
 #include<vector>
 #include<algorithm>
 #define lson l,m
 #define rson m+1,r
 using namespace std;
 const int MAXN=+;
 int n,q,tot,m,d;
 struct node
 {
     int l,r,k,Q;
 }op[MAXN];
 int a[MAXN<<],hash[MAXN<<],T[MAXN<<],S[MAXN<<],use[MAXN<<];
 int L[MAXN<<],R[MAXN<<],sum[MAXN<<];

 int lowbit(int x)
 {
     return (x&(-x));
 }

 int build(int l,int r)
 {
     int rt=++tot;
     sum[rt]=;
     if (l!=r)
     {
         int m=(l+r)>>;
         L[rt]=build(lson);
         R[rt]=build(rson);
     }
     return rt;
 }

 int update(int pre,int l,int r,int x,int op)
 {
     int rt=++tot;
     L[rt]=L[pre],R[rt]=R[pre],sum[rt]=sum[pre]+op;
     if (l<r)
     {
         int m=(l+r)>>;
         if (x<=m) L[rt]=update(L[pre],lson,x,op);
             else R[rt]=update(R[pre],rson,x,op);
     }
     return rt;
 }

 int Sum(int x)
 {
     int ret=;
     while (x>)
     {
         ret+=sum[L[use[x]]];
         x-=lowbit(x);
     }
     return ret;
 }

 int query(int Sl,int Sr,int Tl,int Tr,int l,int r,int k)
 {
     if (l==r) return l;
     int m=(l+r)>>;
     int tmp=Sum(Sr)-Sum(Sl)+sum[L[Tr]]-sum[L[Tl]];
     if (tmp>=k)
     {
         for (int i=Sl;i;i-=lowbit(i)) use[i]=L[use[i]];
         for (int i=Sr;i;i-=lowbit(i)) use[i]=L[use[i]];
         return query(Sl,Sr,L[Tl],L[Tr],lson,k);
     }
     else
     {
         for (int i=Sl;i;i-=lowbit(i)) use[i]=R[use[i]];
         for (int i=Sr;i;i-=lowbit(i)) use[i]=R[use[i]];
         return query(Sl,Sr,R[Tl],R[Tr],rson,k-tmp);
     }
 } 

 void modify(int x,int p,int delta)
 {
     while (x<=n)
     {
         S[x]=update(S[x],,d,p,delta);
         x+=lowbit(x);
     }
 }

 void init()
 {
     tot=;
     m=;
     d=;
     scanf("%d%d",&n,&q);
     for (int i=;i<=n;i++) scanf("%d",&a[i]),hash[++m]=a[i];
     for (int i=;i<q;i++)
     {
         char s[];
         scanf("%s",s);
         if (s[]=='Q')    scanf("%d%d%d",&op[i].l,&op[i].r,&op[i].k),op[i].Q=;
             else
             {
                 scanf("%d%d",&op[i].l,&op[i].r);
                 op[i].Q=;
                 hash[++m]=op[i].r;
             }
     }
     /*因为修改后的数可能不在初始几个数的范围内，故要先输入完查询*/ 

     sort(hash+,hash+m+);
     d=unique(hash+,hash++m)-hash-;

     T[]=build(,d);//T表示每一步T树的树根
     for (int i=;i<=n;i++)
     {
         int x=lower_bound(hash+,hash+d+,a[i])-hash;
         T[i]=update(T[i-],,d,x,);
     }

     for (int i=;i<=n;i++) S[i]=T[];
 }

 void solve()
 {

     for (int i=;i<q;i++)
     {
         if (op[i].Q)
         {
             for (int j=op[i].l-;j;j-=lowbit(j)) use[j]=S[j];
             for (int j=op[i].r;j;j-=lowbit(j)) use[j]=S[j];
             int ans=query(op[i].l-,op[i].r,T[op[i].l-],T[op[i].r],,d,op[i].k);
             printf("%d\n",hash[ans]);
         }
         else
         {
             int x=lower_bound(hash+,hash+d+,a[op[i].l])-hash;
             int y=lower_bound(hash+,hash+d+,op[i].r)-hash;
             modify(op[i].l,x,-);
             modify(op[i].l,y,);
             a[op[i].l] =op[i].r;
         }
     }
 }

 int main()
 {
     init();
     solve();
     return ;
 }