bzoj2588 Spoj 10628. Count on a tree
主席树
1 #include<cstdio> 2 #include<algorithm> 3 #include<map> 4 #define N 2000010 5 using namespace std; 6 map<int,int>ma; 7 int n,m,i,a,b,c,e[N],last,d[N],id[N],deep[N],j; 8 int dp,pre[N],p[N],tt[N],l[N],r[N],ls[N],rs[N],s[N],tot,root[N]; 9 int jump[100100][19]; 10 void link(int x,int y) 11 { 12 dp++;pre[dp]=p[x];p[x]=dp;tt[dp]=y; 13 } 14 void build(int &x,int a,int b) 15 { 16 tot++;x=tot; 17 l[x]=a;r[x]=b; 18 if (b-a>1) 19 { 20 int m=(a+b)>>1; 21 build(ls[x],a,m); 22 build(rs[x],m,b); 23 } 24 } 25 void insert(int &x,int y,int a,int b) 26 { 27 tot++;x=tot; 28 l[x]=l[y];r[x]=r[y]; 29 ls[x]=ls[y];rs[x]=rs[y];s[x]=s[y]; 30 if ((a<=l[x])&&(r[x]<=b)) 31 { 32 s[x]++; 33 return; 34 } 35 int m=(l[x]+r[x])>>1; 36 if (a<m) insert(ls[x],ls[y],a,b); 37 if (m<b) insert(rs[x],rs[y],a,b); 38 s[x]=s[ls[x]]+s[rs[x]]; 39 } 40 void dfs(int x,int fa) 41 { 42 int i=p[x]; 43 insert(root[x],root[fa],e[x]-1,e[x]); 44 jump[x][0]=fa; 45 deep[x]=deep[fa]+1; 46 while (i) 47 { 48 if (tt[i]!=fa) dfs(tt[i],x); 49 i=pre[i]; 50 } 51 } 52 int query(int x,int y,int z,int w,int c) 53 { 54 if (r[x]-l[x]==1) 55 { 56 return r[x]; 57 } 58 int tmp=s[ls[x]]+s[ls[y]]-2*s[ls[z]]; 59 if ((l[ls[x]]<w)&&(w<=r[ls[x]])) tmp++; 60 if (tmp>=c) 61 return query(ls[x],ls[y],ls[z],w,c); 62 else 63 return query(rs[x],rs[y],rs[z],w,c-tmp); 64 } 65 int lca(int a,int b) 66 { 67 int i; 68 if (deep[a]<deep[b]) a^=b^=a^=b; 69 for (i=17;i>=0;i--) 70 if (deep[jump[a][i]]>=deep[b]) a=jump[a][i]; 71 if (a==b) return a; 72 73 for (i=17;i>=0;i--) 74 if (jump[a][i]!=jump[b][i]) 75 { 76 a=jump[a][i]; 77 b=jump[b][i]; 78 } 79 return jump[a][0]; 80 } 81 int main() 82 { 83 scanf("%d%d",&n,&m); 84 for (i=1;i<=n;i++) 85 { 86 scanf("%d",&e[i]); 87 d[i]=e[i]; 88 } 89 sort(d+1,d+1+n);int cnt=0;d[0]=-0x37373737; 90 for (i=1;i<=n;i++) 91 { 92 if (d[i]!=d[i-1]) cnt++; 93 ma[d[i]]=cnt; 94 id[cnt]=d[i]; 95 } 96 for (i=1;i<=n;i++) e[i]=ma[e[i]]; 97 for (i=1;i<n;i++) 98 { 99 scanf("%d%d",&a,&b); 100 link(a,b); 101 link(b,a); 102 } 103 build(root[0],0,cnt); 104 dfs(1,0); 105 106 for (i=1;i<=17;i++) 107 for (j=1;j<=n;j++) 108 jump[j][i]=jump[jump[j][i-1]][i-1]; 109 110 111 int ans=0; 112 for (i=1;i<=m;i++) 113 { 114 scanf("%d%d%d",&a,&b,&c); 115 a^=ans; 116 int LCA=lca(a,b); 117 //printf("%d %d %d\n",s[root[a]],s[root[b]],LCA); 118 ans=id[query(root[a],root[b],root[LCA],e[LCA],c)]; 119 printf("%d",ans); 120 if (i!=m) printf("\n"); 121 } 122 123 }
