BZOJ 2819 DFS序+线段树

非递归的DFS写炸了… 交了一个递归版的 过了………..

//By SiriusRen
#include 
#include 
#include 
using namespace std;
const int N=1000050;
int n,nn,q,xx,yy,stk[N],in[N],out[N],top,cnt,tree[N*4];
int first[N],next[N],v[N],tot,num[N],vis[N],fa[N/2][21];
char ch[5];
struct Node{int deep,id;}node[N];
bool cmpdeep(Node a,Node b){return a.deepreturn a.idint x,int y){v[tot]=y,next[tot]=first[x],first[x]=tot++;}
void insert(int l,int r,int pos,int id,int w){
    if(l==r){tree[pos]=w;return;}
    int mid=(l+r)>>1,lson=pos<<1,rson=pos<<1|1;
    if(mid1,r,rson,id,w);
    else insert(l,mid,lson,id,w);
    tree[pos]=tree[lson]^tree[rson];
}
int query(int l,int r,int pos,int L,int R){
    if(l>=L&&r<=R)return tree[pos];
    int mid=(l+r)>>1,lson=pos<<1,rson=pos<<1|1;
    if(midreturn query(mid+1,r,rson,L,R);
    else if(mid>=R)return query(l,mid,lson,L,R);
    else return query(l,mid,lson,L,R)^query(mid+1,r,rson,L,R);
}
int lca(int x,int y){
    if(node[x].deepy].deep)swap(x,y);
    for(int i=20;~i;i--)if(node[x].deep-(1<=node[y].deep)x=fa[x][i];
    if(x==y)return x;
    for(int i=20;~i;i--)if(fa[x][i]!=fa[y][i])x=fa[x][i],y=fa[y][i];
    return fa[x][0];
}
void dfs(int x){
    in[x]=++cnt,insert(0,nn,1,cnt,num[x]); 
    for(int i=first[x];~i;i=next[i])if(!vis[v[i]]){
        vis[v[i]]=1,node[v[i]].deep=node[x].deep+1;
        fa[v[i]][0]=x;
        dfs(v[i]);
    }
    out[x]=++cnt,insert(0,nn,1,cnt,num[x]);
}
int main(){
    memset(first,-1,sizeof(first)),vis[1]=1;
    scanf("%d",&n),nn=n*2;
    for(int i=1;i<=n;i++)scanf("%d",&num[i]),node[i].id=i;
    for(int i=1;i"%d%d",&xx,&yy),add(xx,yy),add(yy,xx);
    node[1].deep=vis[1]=1;
    dfs(1);
    sort(node+1,node+1+n,cmpdeep);
    for(int i=1;i<=n;i++)
        for(int j=1;j<=20;j++)
            fa[node[i].id][j]=fa[fa[node[i].id][j-1]][j-1];
    sort(node+1,node+1+n,cmpid);
    scanf("%d",&q);
    for(int i=1;i<=q;i++){
        scanf("%s",ch);
        if(ch[0]=='Q'){
            scanf("%d%d",&xx,&yy);
            puts(query(0,nn,1,0,in[xx])^query(0,nn,1,0,in[yy])^num[lca(xx,yy)]?"Yes":"No");
        }
        else{
            scanf("%d%d",&xx,&yy),num[xx]=yy;
            insert(0,nn,1,in[xx],yy),insert(0,nn,1,out[xx],yy);
        }
    }
}

转载于:https://www.cnblogs.com/SiriusRen/p/6532052.html