【字典树】 HDOJ 4825 Xor Sum

建立字典树就可以快速查找了。。。

#include <iostream>
#include <queue> 
#include <stack> 
#include <map> 
#include <set> 
#include <bitset> 
#include <cstdio> 
#include <algorithm> 
#include <cstring> 
#include <climits>
#include <cstdlib>
#include <cmath>
#include <time.h>
#define maxn 5000005
#define maxm 4000005
#define eps 1e-10
#define mod 1000000007
#define INF 1e9
#define lowbit(x) (x&(-x))
#define mp make_pair
#define ls o<<1
#define rs o<<1 | 1
#define lson o<<1, L, mid 
#define rson o<<1 | 1, mid+1, R 
typedef long long LL;
typedef unsigned long long ULL;
//typedef int LL;
using namespace std;

struct node
{
	LL x;
	node *next[2];
}*top, *root, pool[maxm], *now;
int n, m;

node* newnode(void)
{
	top->x = 0;
	top->next[0] = top->next[1] = NULL;
	return top++;
}

void init(void)
{
	top = pool;
	root = newnode();
}

void insert(LL x)
{
	now = root;
	for(int i = 59; i >= 0; i--) {
		int t = (x >> i) & 1;
		if(!now->next[t]) now->next[t] = newnode();
		now = now->next[t];
	}
	now->x = x;
}

void read(void)
{
	LL x;
	scanf("%d%d", &n, &m);
	for(int i = 1; i <= n; i++) {
		scanf("%I64d", &x);
		insert(x);
	}
}

void work(void)
{
	LL x;
	while(m--) {
		scanf("%I64d", &x);
		now = root;
		for(int i = 59; i >= 0; i--) {
			int t = (x >> i) & 1;
			t ^= 1;
			if(now->next[t]) now = now->next[t];
			else now = now->next[t^1];
			//printf("%d\n", t);
		}
		printf("%I64d\n", now->x);
	}
}

int main(void)
{
	int _, __;
	while(scanf("%d", &_)!=EOF) {
		__ = 0;
		while(_--) {
			init();
			read();
			printf("Case #%d:\n", ++__);
			work();
		}
	}

	return 0;
}