【BZOJ 4568】 4568: [Scoi2016]幸运数字 （线性基+树链剖分+线段树）

  1 #include<cstdio>
  2 #include<cstdlib>
  3 #include<cstring>
  4 #include<iostream>
  5 #include<algorithm>
  6 using namespace std;
  7 #define Maxn 20010
  8 #define LL long long
  9 
 10 LL a[Maxn],aa[Maxn];
 11 
 12 struct nnode
 13 {
 14     int x,y,next;
 15 }t[Maxn*2];
 16 int len,first[Maxn];
 17 
 18 void ins(int x,int y)
 19 {
 20     t[++len].x=x;t[len].y=y;
 21     t[len].next=first[x];first[x]=len;
 22 }
 23 
 24 int fa[Maxn],son[Maxn],sm[Maxn],dep[Maxn];
 25 void dfs1(int x,int ff)
 26 {
 27     son[x]=0;fa[x]=ff;sm[x]=1;
 28     dep[x]=dep[ff]+1;
 29     for(int i=first[x];i;i=t[i].next) if(t[i].y!=ff)
 30     {
 31         int y=t[i].y;
 32         dfs1(y,x);
 33         sm[x]+=sm[y];
 34         if(son[x]==0||sm[y]>sm[son[x]]) son[x]=y;
 35     }
 36 }
 37 
 38 int dfn[Maxn],tp[Maxn],cnt;
 39 void dfs2(int x,int tpp)
 40 {
 41     tp[x]=tpp;dfn[x]=++cnt;
 42     aa[cnt]=a[x];
 43     if(son[x]) dfs2(son[x],tpp);
 44     for(int i=first[x];i;i=t[i].next) if(t[i].y!=fa[x]&&t[i].y!=son[x])
 45     {
 46         int y=t[i].y;
 47         dfs2(y,y);
 48     }
 49 }
 50 
 51 struct node
 52 {
 53     int l,r,lc,rc;
 54     LL w[61];
 55 }tr[Maxn*2];
 56 
 57 void ist(int x,LL y)
 58 {
 59     for(int i=60;i>=0;i--) if((1LL<<i)&y)
 60     {
 61         if(tr[x].w[i]) y^=tr[x].w[i];
 62         else {tr[x].w[i]=y;break;}
 63     }
 64 }
 65 
 66 void merge(int x,int y)
 67 {
 68     for(int i=0;i<=60;i++) if(tr[y].w[i]!=0) ist(x,tr[y].w[i]);
 69 }
 70 
 71 int tot;
 72 int build(int l,int r)
 73 {
 74     int x=++tot;
 75     tr[x].l=l;tr[x].r=r;
 76     memset(tr[x].w,0,sizeof(tr[x].w));
 77     if(l!=r)
 78     {
 79         int mid=(l+r)>>1;
 80         tr[x].lc=build(l,mid);
 81         tr[x].rc=build(mid+1,r);
 82         merge(x,tr[x].lc);
 83         merge(x,tr[x].rc);
 84     }
 85     else
 86     {
 87         tr[x].lc=tr[x].rc=0;
 88         ist(x,aa[l]);
 89     }
 90     return x;
 91 }
 92 
 93 void query(int x,int l,int r)
 94 {
 95     if(tr[x].l==l&&tr[x].r==r)
 96     {
 97         merge(0,x);
 98         return;
 99     }
100     int mid=(tr[x].l+tr[x].r)>>1;
101     if(r<=mid) query(tr[x].lc,l,r);
102     else if(l>mid) query(tr[x].rc,l,r);
103     else
104     {
105         query(tr[x].lc,l,mid);
106         query(tr[x].rc,mid+1,r);
107     }
108 }
109 
110 LL fquery(int x,int y)
111 {
112     memset(tr[0].w,0,sizeof(tr[0].w));
113     while(tp[x]!=tp[y])
114     {
115         if(dep[tp[x]]<dep[tp[y]]) swap(x,y);
116         query(1,dfn[tp[x]],dfn[x]);
117         x=fa[tp[x]];
118     }
119     if(dep[x]<dep[y]) swap(x,y);
120     query(1,dfn[y],dfn[x]);
121     LL ans=0;
122     for(int i=60;i>=0;i--) if((ans^tr[0].w[i])>ans) ans^=tr[0].w[i];
123     return ans;
124 }
125 
126 int main()
127 {
128     int n,q;
129     scanf("%d%d",&n,&q);
130     len=0;
131     memset(first,0,sizeof(first));
132     for(int i=1;i<=n;i++) scanf("%lld",&a[i]);
133     for(int i=1;i<n;i++)
134     {
135         int x,y;
136         scanf("%d%d",&x,&y);
137         ins(x,y);ins(y,x);
138     }
139     dep[0]=0;
140     dfs1(1,0);cnt=0;
141     dfs2(1,1);tot=0;
142     build(1,n);
143     for(int i=1;i<=q;i++)
144     {
145         int x,y;
146         scanf("%d%d",&x,&y);
147         printf("%lld\n",fquery(x,y));
148     }
149     return 0;
150 }