玲珑学院OJ 1028 - Bob and Alice are playing numbers 字典树，dp

http://www.ifrog.cc/acm/problem/1028

题解处：http://www.ifrog.cc/acm/solution/4

#include <cstdio>
#include <cstring>
#include <queue>
#include <cmath>
#include <algorithm>
using namespace std;
typedef long long LL;
const int N = 1e5 + ;
const double eps = 1e-;
const double INF = 1e12;
int ch[N*][],cnt[N*],tot,a[N],n,T,op,kase;
bool dp[(<<)+];
inline int newnode(){
  ++tot;
  ch[tot][]=ch[tot][]=-;
  cnt[tot]=;
  return tot;
}
void insert(int x){
  int ptr = ;
  for(int i=;i>=;--i){
    int nx = (x&(<<i))?:;
    if(ch[ptr][nx]==-)
      ch[ptr][nx]=newnode();
    ptr = ch[ptr][nx];++cnt[ptr];
  }
}
void Union(int &x,int y){
  if(y==-)return;
  if(x==-)x = newnode();
  cnt[x]+=cnt[y];
  Union(ch[x][],ch[y][]);
  Union(ch[x][],ch[y][]);
}
int ask_xor(int x){
   int ret=,ptr=;
   for(int i=;i>=;--i){
      int nx = (x&(<<i))?:;
      if(ch[ptr][nx^]!=-){
        ret|=(<<i);
        ptr=ch[ptr][nx^];
      }
      else ptr=ch[ptr][nx];
      if(ptr==-)break;
   }
   return ret;
}
int ask_and(){
  int ret=,ptr=;
  for(int i=;i>=;--i){
    if(ch[ptr][]!=-&&cnt[ch[ptr][]]>=)
      ret|=(<<i);
    else Union(ch[ptr][],ch[ptr][]);
    ptr=ch[ptr][];
  }
  return ret;
}
void ask_or(){
  memset(dp,false,sizeof(dp));
  for(int i=;i<=n;++i)dp[a[i]]=true;
  for(int i=(<<);i>=;--i){
    for(int j=;j<=;++j)
      if(!(i&(<<j)))dp[i]|=dp[i|(<<j)];
  }
  int ret=,p=;
  int tmp[];
  for(int i=;i<=n;++i){
    p=;
    for(int j=;j>=;--j)
      if(!(a[i]&(<<j)))tmp[++p]=(<<j);
    int x=;
    for(int j=;j<=p;++j){
      if(dp[x|tmp[j]])x|=tmp[j];
    }
    ret=max(ret,x|a[i]);
  }
  printf("%d\n",ret);
}
int main(){
  scanf("%d",&T);
  while(T--){
    scanf("%d%d",&n,&op);
    tot=-;newnode();int ret_xor=;
    for(int i=;i<=n;++i){
      scanf("%d",&a[i]);
      if(op==)ret_xor=max(ret_xor,ask_xor(a[i]));
      insert(a[i]);
    }
    printf("Case #%d: ",++kase);
    if(op==)printf("%d\n",ret_xor);
    else if(op==)printf("%d\n",ask_and());
    else ask_or();
  }
  return ;
}