我不理解为什么有人说一定要快读

#include<vector>
#include<cstdio>
#include<limits>


class Trie
{
	public:
		typedef std::size_t NodeId;
		static constexpr NodeId NIL=static_cast<NodeId>(-1);
	private:
		struct TrieNode
		{
			NodeId zero;
			NodeId one;
			inline constexpr TrieNode():zero(NIL),one(NIL){}
		};
		
		std::vector<TrieNode> child;
		
	public:
		inline Trie():child(1ull){}
		
		bool hasChild(NodeId parent,bool childValue){
			if(childValue && child.at(parent).one==NIL) return false;
			else if(!childValue && child.at(parent).zero==NIL) return false;
			else return true;
		}
		
		NodeId getChild(NodeId parent,bool childValue){
			if(childValue) return child.at(parent).one;
			else return child.at(parent).zero;
		}
		
		void insertNode(NodeId parent,bool childValue){
			if(childValue && child.at(parent).one==NIL){
				child.at(parent).one=child.size();
				child.emplace_back();
			}else if(!childValue && child.at(parent).zero==NIL){
				child.at(parent).zero=child.size();
				child.emplace_back();
			}
		}
		
		static inline constexpr NodeId getRootId(){
			return 0ull;
		}
		
		void insertNumber(int x){
			int u=this->getRootId();
			for(int i=31;i>=0;i--){
				bool bit=static_cast<bool>((x>>i)&1);
				this->insertNode(u,bit);
				u=this->getChild(u,bit);
			}
		}
		
		int findXor(int x){
			int u=this->getRootId(),res=0;
			for(int i=31;i>=0;i--){
				if(u==NIL) u=0;
				bool bit=static_cast<bool>((x>>i)&1);
				if(this->hasChild(u,!bit)){
					u=this->getChild(u,!bit);
					res+=1<<i;
				}else{
					u=this->getChild(u,bit);
				}
			}
			return res;
		}
};


int main(){
	int n,ans=std::numeric_limits<int>::min();
	scanf("%d",&n);
	int *a=new int[n];
	Trie* tr=new Trie;
	for(int i=0;i<n;i++){
		scanf("%d",a+i);
		tr->insertNumber(a[i]);
	}
	for(int i=0;i<n;i++){
		ans=std::max(ans,tr->findXor(a[i]));
	}
	printf("%d",ans);
	delete tr;
	delete []a;
	return 0;
}