BZOJ3306: 树

  1 #include<cstdio>
  2 
  3 #include<cstdlib>
  4 
  5 #include<cmath>
  6 
  7 #include<cstring>
  8 
  9 #include<algorithm>
 10 
 11 #include<iostream>
 12 
 13 #include<vector>
 14 
 15 #include<map>
 16 
 17 #include<set>
 18 
 19 #include<queue>
 20 
 21 #include<string>
 22 
 23 #define inf 1000000000
 24 
 25 #define maxn 250000+5
 26 
 27 #define maxm 500+100
 28 
 29 #define eps 1e-10
 30 
 31 #define ll long long
 32 
 33 #define pa pair<int,int>
 34 
 35 #define for0(i,n) for(int i=0;i<=(n);i++)
 36 
 37 #define for1(i,n) for(int i=1;i<=(n);i++)
 38 
 39 #define for2(i,x,y) for(int i=(x);i<=(y);i++)
 40 
 41 #define for3(i,x,y) for(int i=(x);i>=(y);i--)
 42 
 43 #define mod 1000000007
 44 
 45 using namespace std;
 46 
 47 inline int read()
 48 
 49 {
 50 
 51     int x=0,f=1;char ch=getchar();
 52 
 53     while(ch<‘0‘||ch>‘9‘){if(ch==‘-‘)f=-1;ch=getchar();}
 54 
 55     while(ch>=‘0‘&&ch<=‘9‘){x=10*x+ch-‘0‘;ch=getchar();}
 56 
 57     return x*f;
 58 
 59 }
 60 int n,m,q,rt,tot,l[maxn],r[maxn],id[maxn],w[maxn],f[maxn][50],dep[maxn],head[maxn];
 61 struct seg{int l,r,mi;}t[4*maxn];
 62 struct edge{int go,next;}e[maxn];
 63 inline void insert(int x,int y)
 64 {
 65     e[++tot]=(edge){y,head[x]};head[x]=tot;
 66 }
 67 inline void dfs(int x)
 68 {
 69     l[x]=++m;id[m]=x;
 70     for1(i,18)if((1<<i)<=dep[x])f[x][i]=f[f[x][i-1]][i-1];else break;
 71     for(int i=head[x];i;i=e[i].next)
 72     {
 73         int y=e[i].go;f[y][0]=x;dep[y]=dep[x]+1;
 74         dfs(y);
 75     }
 76     r[x]=m;
 77 }
 78 inline void pushup(int k)
 79 {
 80     t[k].mi=min(t[k<<1].mi,t[k<<1|1].mi);
 81 }
 82 inline void build(int k,int l,int r)
 83 {
 84     t[k].l=l;t[k].r=r;int mid=(l+r)>>1;
 85     if(l==r){t[k].mi=w[id[l]];return;}
 86     build(k<<1,l,mid);build(k<<1|1,mid+1,r);
 87     pushup(k);
 88 }
 89 inline void change(int k,int x,int y)
 90 {
 91     int l=t[k].l,r=t[k].r,mid=(l+r)>>1;
 92     if(l==r){t[k].mi=y;return;}
 93     if(x<=mid)change(k<<1,x,y);else change(k<<1|1,x,y);
 94     pushup(k);
 95 }
 96 inline int query(int k,int x,int y)
 97 {
 98     int l=t[k].l,r=t[k].r,mid=(l+r)>>1;
 99     if(l==x&&r==y)return t[k].mi;
100     if(y<=mid)return query(k<<1,x,y);
101     else if(x>mid)return query(k<<1|1,x,y);
102     else return min(query(k<<1,x,mid),query(k<<1|1,mid+1,y));
103 }
104 
105 int main()
106 
107 {
108 
109     //freopen("input.txt","r",stdin);
110 
111     //freopen("output.txt","w",stdout);
112 
113     n=read();q=read();
114     for1(i,n)insert(read(),i),w[i]=read();
115     dfs(1);
116     build(1,1,m);rt=1;
117     while(q--)
118     {
119         char ch=getchar();int x=read();
120         if(ch==‘V‘)change(1,l[x],read());
121         else if(ch==‘E‘)rt=x;
122         else 
123         {
124             int y=rt;
125             if(x==y)printf("%d\n",t[1].mi);
126             else if(l[x]<=l[y]&&r[x]>=r[y])
127             {
128                 int t=dep[y]-dep[x]-1;
129                 for0(i,18)if(t&(1<<i))y=f[y][i];
130                 int ans=inf;
131                 if(l[1]<=l[y]-1)ans=min(ans,query(1,l[1],l[y]-1));
132                 if(r[y]+1<=r[1])ans=min(ans,query(1,r[y]+1,r[1]));
133                 printf("%d\n",ans);
134             }
135             else printf("%d\n",query(1,l[x],r[x]));
136         }
137     }
138 
139     return 0;
140 
141 }