HDU 5536 Chip Factory 带删除的01字典树

题目链接

思路

#include<cstdio>
#include<iostream>
#include<algorithm>
#include<cstring>
#include<vector>
#include<string>
#include<queue>
#include<stack>
#include<set>
#include<map>
#define ll long long
using namespace std;
const int INF = ( 2e9 ) + 2;
const ll maxn = 1e3+100;
int val[maxn];
int t[maxn*33][2];
int cnt[maxn*33][2];
int tot;
void insert(int rt,int st,int a)
{
if(st==-1)return;
int cur=(a>>st)&1;
cnt[rt][cur]++;
if(!t[rt][cur])t[rt][cur]=++tot,t[tot][0]=0,t[tot][1]=0,cnt[tot][0]=0,cnt[tot][1]=0;
insert(t[rt][cur],st-1,a);
}
void erase(int rt,int st,int a)
{
if(st==-1)return;
int cur=(a>>st)&1;
cnt[rt][cur]--;
erase(t[rt][cur],st-1,a);
}
int find(int rt,int st,int a)
{
if(st==-1)return 0;
int cur=(a>>st)&1;
if(cnt[rt][cur^1]>0)return (1<<st)+find(t[rt][cur^1],st-1,a);
else return find(t[rt][cur],st-1,a);
}
int main()
{
int T,n;
scanf("%d",&T);
while(T--)
{
scanf("%d",&n);
t[0][0]=t[0][1]=0;
cnt[0][0]=cnt[0][1]=0;
tot=0;
for(int i=1;i<=n;i++)
{
scanf("%d",&val[i]);
insert(0,30,val[i]);
}
int mx=0;
for(int i=1;i<=n;i++)
{
erase(0,30,v
ca93
al[i]);
for(int j=i+1;j<=n;j++)
{
erase(0,30,val[j]);
mx=max(mx,find(0,30,val[i]+val[j]));
insert(0,30,val[j]);
}
insert(0,30,val[i]);
}
printf("%d\n",mx);
}
}