正题
ybtoj Trie-2

---

题目大意

给你n个数，选择2个，使其异或值最大

---

解题思路

对于每个数的二进制建立Trie，然后每个数在Trie中搜索，每次尽量走不同方向

---

代码

#include<cstdio>
#include<cstring>
#include<iostream>
#include<algorithm>
#define ll long long
#define N 100100
using namespace std;
int n, x, w, ans, to[N*32][2];
void insert(int x)
{int now = 0, y;for (int i = 30; i >= 0; --i){y = (x>>i)&1;if (!to[now][y]) to[now][y] = ++w;now = to[now][y];}return;
}
int ask(int x)
{int ans = 0, now = 0, y = 0;for (int i = 30; i >= 0; --i){y = (x>>i)&1^1;//走不同方向if (to[now][y]) ans += 1<<i;else y ^= 1;now = to[now][y];}return ans;
}
int main()
{scanf("%d", &n);for (int i = 1; i <= n; ++i){scanf("%d",&x);ans = max(ans, ask(x));insert(x);}printf("%d", ans);return 0;
}