HDU 3974 assign the task (DFS number + segment tree segment update)

It specifies the relationship between the upper and lower levels of a point. If task a is assigned to I, all its subordinates will be assigned. They all stopped their work and started to do.

Operate t x y to assign x task y and c x to ask about the current task of X;

Sample Input

 1 5 4 3 3 2 1 3 5 2 5 C 3 T 2 1 C 3 T 3 2 C 3 

Sample output

 Case #1:-1 1 2 

Ideas:

The DFS depth is used to traverse and rename the node to make the son of a node continuous. Then update the data in segments.

2:1-5

5: 2-2

PM-5

-4

PM-5 pm

#include<iostream>#include<cstring>#include<cstdio>#include<cstdlib>#define lson l,m,rt<<1#define rson m+1,r,rt<<1|1#define N 50001using namespace std;int lazy[N<<2];int task[N<<2];int next[N],pre[N],to[N];int uset[N];int num;int l[N],r[N];int find_set(int x){    while(uset[x]!=x)        x=uset[x];    return x;}void dfs(int root){    int i=pre[root];    l[root]=(++num);    while(i!=-1)    {        dfs(to[i]);        i=next[i];    }    r[root]=num;}void pushdown(int rt){    if(lazy[rt]!=-1)    {        task[rt<<1]=lazy[rt];        lazy[rt<<1]=lazy[rt];        task[rt<<1|1]=lazy[rt];        lazy[rt<<1|1]=lazy[rt];        lazy[rt]=-1;    }}void build(int l,int r,int rt){    task[rt]=-1;    lazy[rt]=-1;    if(l==r)        return;    int m=(l+r)>>1;    build(lson);    build(rson);}void update(int L,int R,int l,int r,int rt,int val){    if(L<=l&&r<=R)    {        lazy[rt]=val;        task[rt]=val;        return;    }    pushdown(rt);    int m=(r+l)>>1;    if(L<=m) update(L,R,lson,val);    if(R>m) update(L,R,rson,val);}void query(int L,int R,int l,int r,int rt){    if(L<=l&&r<=R)    {        printf("%d\n",task[rt]);        return;    }    pushdown(rt);    int m=(l+r)>>1;    if(L<=m) query(L,R,lson);    if(R>m) query(L,R,rson);}int main(){    int T;    scanf("%d",&T);    for(int cas=1;cas<=T;cas++)    {        int n;        int u,v;        scanf("%d",&n);        for(int i=1;i<=n;i++)        {            uset[i]=i;            pre[i]=-1;        }        for(int i=1;i<n;i++)        {            scanf("%d%d",&u,&v);            uset[u]=v;            to[i]=u;            next[i]=pre[v];            pre[v]=i;        }        int root=find_set(1);        num=0;        dfs(root);        //for(int i=1;i<=num;i++)        //    printf("%d -- %d  %d\n",i,l[i],r[i]);        //system("pause");        build(1,num,1);        int m;        int a,b;        char op[10];        scanf("%d",&m);        printf("Case #%d:\n",cas);        for(int i=0;i<m;i++)        {            scanf("%s",&op);            if(op[0]=='C')            {                scanf("%d",&a);                query(l[a],l[a],1,num,1);            }            else            {                scanf("%d %d",&a,&b);                update(l[a],r[a],1,num,1,b);            }        }    }    return 0;}

HDU 3974 assign the task (DFS number + segment tree segment update)