bzoj1146: [CTSC2008]网络管理Network 树套树

我还是太弱了，第一次碰主席树带删除的操作。首先我们按题目要求建一棵主席树(主席树只会是记前缀和)，然后像COT那样用dfs序来维护，接着删除操作只是在树状数组上进行，树状数组只是记录每个点在原值的基础上加或减了多少。我们可以开个数组把子树都记下来，然后在二分的时候一边二分一边向下走就可以了。

#include <cstdio>#include <cstring>#include <iostream>#include <algorithm>#include <vector>using namespace std;#define N 100010#define M 8000010int w[N],a[N],b[N],c[N],san[N],A[N],B[N],C[N],vis[N],lca[N],lft[N],rht[N],first[N],fa[N],f[N],root[N];int sum[M],ls[M],rs[M];int n,m,tot,cnt,ne,siz,tim,numa,numb;vector<pair<int,int> > ask[N];struct edge{int y,next;}e[N << 1];void addedge(int x,int y){   e[++ cnt].next = first[x];e[cnt].y = y;first[x] = cnt;   e[++ cnt].next = first[y];e[cnt].y = x;first[y] = cnt;}char ch;void read(int &x){   while (ch = getchar(),ch < '0' || ch > '9');   x = ch - '0';   while (ch = getchar(),ch >= '0' && ch <= '9') x = x * 10 + ch - '0';}void update(int x,int &rt,int l,int r,int y,int k){    int mid=(l+r)>>1;    if(rt==0)    {        siz++;        rt=siz;        ls[rt]=ls[x];        rs[rt]=rs[x];        sum[rt]=sum[x];        if(y<=mid) ls[rt]=0;        else rs[rt]=0;    }    sum[rt]+=k;    if(l==r) return;    if(y<=mid) update(ls[x],ls[rt],l,mid,y,k);    else update(rs[x],rs[rt],mid+1,r,y,k);}int find(int x){    return x == fa[x] ? x : fa[x] = find(fa[x]);}void dfs(int x){    update(root[f[x]],root[x],1,tot,w[x],1);    tim++;    lft[x]=tim;fa[x]=x;    for(int i = first[x];i;i = e[i].next)    if(e[i].y != f[x])        {            f[e[i].y] = x;            dfs(e[i].y);            fa[e[i].y] = x;        }    rht[x] = tim;    vis[x] = 1;    int t = ask[x].size();    for (int i = 0;i < t;i ++)        if (vis[ask[x][i].first])        {            lca[ask[x][i].second] = find(ask[x][i].first);        }}int lowbit(int x){    return x&(-x);}void getbit(int x,int p){    if(p)    {        numa++;a[numa]=root[x];        x = lft[x];        while(x)        {            numa++;a[numa]=c[x];            x-=lowbit(x);        }    }    else    {        numb++;b[numb]=root[x];        x = lft[x];        while(x)        {            numb++;b[numb]=c[x];            x-=lowbit(x);        }    }}void addup(int x,int pos,int val){    while(x<=n)    {        int tmp=0;        update(c[x],tmp,1,tot,pos,val);        c[x]=tmp;        x+=lowbit(x);    }}int query(int k){    int t,tt,l = 1,r = tot;    while (l < r)    {        t = 0,tt = 0;        for (int i = 1;i <= numa;i ++) t += sum[rs[a[i]]],tt += sum[a[i]];        for (int i = 1;i <= numb;i ++) t -= sum[rs[b[i]]],tt -= sum[b[i]];        if (tt < k) return -1;        if (k <= t)        {            for (int i = 1;i <= numa;i ++) a[i] = rs[a[i]];            for (int i = 1;i <= numb;i ++) b[i] = rs[b[i]];            l = (l + r >> 1) + 1;        }        else        {            for (int i = 1;i <= numa;i ++) a[i] = ls[a[i]];            for (int i = 1;i <= numb;i ++) b[i] = ls[b[i]];            r = l + r >> 1;            k -= t;        }    }    return l;}int main(){    read(n);read(m);    int x,y,mid;    for (int i = 1;i <= n;i ++) read(w[i]),san[++ tot] = w[i];    for (int i = 1;i < n;i ++) read(x),read(y),addedge(x,y);    for (int i = 1;i <= m;i ++)    {        read(A[i]);read(B[i]);read(C[i]);        if (!A[i])san[++ tot] = C[i];        else ask[B[i]].push_back(make_pair(C[i],i)),ask[C[i]].push_back(make_pair(B[i],i));    }    sort(san + 1,san + 1 + tot);    tot = unique(san + 1,san + 1 + tot) - san - 1;    for (int i = 1;i <= n;i ++) w[i] = lower_bound(san + 1,san + tot + 1,w[i]) - san;    dfs((n + 1) / 2);    for (int i = 1;i <= m;i ++)    {        if (A[i])        {            x = B[i],y = C[i],mid = lca[i];            numa = numb = 0;            getbit(x,1),getbit(y,1);            getbit(mid,0),getbit(f[mid],0);            x = query(A[i]);            if(x < 0) puts("invalid request!");            else printf("%d\n",san[x]);        }        else        {            x = B[i],y = C[i];            y = lower_bound(san + 1,san + tot + 1,y) - san;            addup(lft[x],w[x],-1);            addup(rht[x]+1,w[x],1);            addup(lft[x],y,1);            addup(rht[x]+1,y,-1);            w[x] = y;        }    }   return 0;}