BZOJ1036 [ZJOI2008]树的统计Count

  1 #include<cstdio>
  2 #include<algorithm>
  3 using namespace std;
  4 const int maxn=30010,inf=1000000000;
  5 struct ee{int to,next;}e[maxn*2];
  6 struct tree{int l,r,mx,sum;}tr[maxn*4];
  7 int cnt,v[maxn],head[maxn],size[maxn],deep[maxn],fa[maxn][20],pos[maxn],belong[maxn],n,sz;
  8 bool vis[maxn];
  9 void insert(int x,int y){
 10     e[++cnt].to=y;e[cnt].next=head[x];head[x]=cnt;
 11     e[++cnt].to=x;e[cnt].next=head[y];head[y]=cnt;
 12 }
 13 
 14 void init(){
 15     scanf("%d",&n);
 16     for (int i=1;i<n;i++){
 17         int x,y;
 18         scanf("%d%d",&x,&y);
 19         insert(x,y);
 20     }
 21     for (int i=1;i<=n;i++) scanf("%d",&v[i]);
 22 }
 23 
 24 void dfs1(int x){
 25     vis[x]=size[x]=1;
 26     for (int i=1;i<=14;i++){
 27         if (deep[x]<(1<<i)) break;
 28         fa[x][i]=fa[fa[x][i-1]][i-1];
 29     }
 30     for (int i=head[x];i;i=e[i].next){
 31         if (vis[e[i].to]) continue;
 32         deep[e[i].to]=deep[x]+1;
 33         fa[e[i].to][0]=x;
 34         dfs1(e[i].to);
 35         size[x]+=size[e[i].to];
 36     }
 37 }
 38 
 39 void dfs2(int x,int chain){
 40     pos[x]=++sz;belong[x]=chain;
 41     int k=0;
 42     for (int i=head[x];i;i=e[i].next) 
 43         if (deep[e[i].to]>deep[x]&&size[e[i].to]>size[k]) k=e[i].to;
 44     if (k==0) return;
 45     dfs2(k,chain);
 46     for (int i=head[x];i;i=e[i].next)
 47         if (deep[e[i].to]>deep[x]&&k!=e[i].to) dfs2(e[i].to,e[i].to);
 48 }
 49 
 50 int lca(int x,int y){
 51     if (deep[x]<deep[y]) swap(x,y);
 52     int t=deep[x]-deep[y];
 53     for (int i=0;i<=14;i++) if (t&(1<<i)) x=fa[x][i];
 54     for (int i=14;i>=0;i--) if (fa[x][i]!=fa[y][i])
 55         x=fa[x][i],y=fa[y][i];
 56     if (x==y) return x;return (fa[x][0]);
 57 }
 58 
 59 void build(int k,int l,int r){
 60     tr[k].l=l;tr[k].r=r;
 61     if (l==r) return;
 62     int mid=(l+r)>>1;
 63     build(k<<1,l,mid);
 64     build(k<<1|1,mid+1,r);
 65 }
 66 
 67 void change(int k,int x,int y){
 68     int l=tr[k].l,r=tr[k].r,mid=(l+r)>>1;
 69     if (l==r) {tr[k].sum=tr[k].mx=y;return;}
 70     if (x>mid) change(k<<1|1,x,y);
 71     else change(k<<1,x,y);
 72     tr[k].sum=tr[k<<1].sum+tr[k<<1|1].sum;
 73     tr[k].mx=max(tr[k<<1].mx,tr[k<<1|1].mx);
 74 }
 75 
 76 int trmax(int k,int x,int y){
 77     if (tr[k].l==x&&tr[k].r==y) return tr[k].mx;
 78     int mid=(tr[k].l+tr[k].r)>>1;
 79     if (x>mid) return trmax(k<<1|1,x,y);
 80     else if (y<=mid) return trmax(k<<1,x,y);
 81     else return max(trmax(k<<1,x,mid),trmax(k<<1|1,mid+1,y)); 
 82 }
 83 
 84 int trsum(int k,int x,int y){
 85     if (tr[k].l==x&&tr[k].r==y) return tr[k].sum;
 86     int mid=(tr[k].l+tr[k].r)>>1;
 87     if (x>mid) return trsum(k<<1|1,x,y);
 88     else if (y<=mid) return trsum(k<<1,x,y);
 89     else return trsum(k<<1,x,mid)+trsum(k<<1|1,mid+1,y);
 90 }
 91 
 92 int solvemx(int x,int f){
 93     int mx=-inf;
 94     while (belong[x]!=belong[f]){//这里是while不是if
 95         mx=max(mx,trmax(1,pos[belong[x]],pos[x]));
 96         x=fa[belong[x]][0];
 97     }
 98     mx=max(mx,trmax(1,pos[f],pos[x]));
 99     return mx;
100 }
101 
102 int solvesum(int x,int f){
103     int sum=0;
104     while (belong[x]!=belong[f]){
105         sum+=trsum(1,pos[belong[x]],pos[x]);
106         x=fa[belong[x]][0];
107         //printf("%d\n",sum);
108     }
109     sum+=trsum(1,pos[f],pos[x]);
110     return sum;
111 }
112 
113 void solve(){
114     build(1,1,n);
115     for (int i=1;i<=n;i++) change(1,pos[i],v[i]);
116     char ch[6]; int x,y,q;
117     scanf("%d",&q);
118     for (int i=0;i<q;i++){
119         scanf("%s%d%d",ch,&x,&y);
120         if (ch[0]==‘C‘) change(1,pos[x],y),v[x]=y;
121         else {
122             int t1=lca(x,y);
123             if (ch[1]==‘M‘) printf("%d\n",max(solvemx(x,t1),solvemx(y,t1)));
124             else printf("%d\n",solvesum(x,t1)+solvesum(y,t1)-v[t1]);
125         }
126     }
127 }
128 
129 int main(){
130     init();
131     dfs1(1);
132     dfs2(1,1);
133     solve();
134 }