提出 #42959371

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ソースコード 拡げる

// LUOGU_RID: 113310813
#include <bits/stdc++.h>
#define SZ(x) (int) x.size() - 1
#define all(x) x.begin(), x.end()
#define ms(x, y) memset(x, y, sizeof x)
#define F(i, x, y) for (int i = (x); i <= (y); i++)
#define DF(i, x, y) for (int i = (x); i >= (y); i--)
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
template <typename T> void chkmax(T& x, T y) { x = max(x, y); }
template <typename T> void chkmin(T& x, T y) { x = min(x, y); }
template <typename T> void read(T &x) {
	x = 0; int f = 1; char c = getchar();
	for (; !isdigit(c); c = getchar()) if (c == '-') f = -f;
	for (; isdigit(c); c = getchar()) x = x * 10 + c - '0';
	x *= f;
}
const int N = 2e5 + 10;
int n, a[N], t[N * 33][2], tot = 1, sz[N * 33], s;
void insert(int x) {
	int num = 1; sz[1]++;
	DF(i, 30, 0) {
		int k = (x >> i) & 1;
		// if (i == 8) cout << k << '\n';
		if (!t[num][k]) t[num][k] = ++tot;
		num = t[num][k];
		sz[num]++;
	}
}
int query(int num1, int num2, int d, int x) {
	if (!num1 || !num2) return 0;
	if (d < 0) return min(sz[num1], sz[num2]);
	if (x & (1 << d)) return query(t[num1][0], t[num2][1], d - 1, x) + query(t[num1][1], t[num2][0], d - 1, x);
	int a = query(t[num1][0], t[num2][0], d - 1, x), b = query(t[num1][1], t[num2][1], d - 1, x);
	// cout << "# " << d << " " << a << " " << b << endl;
	// if (sz[t[num1][0]] - a < sz[t[num2][1]] - b && )
	return a + b + min(sz[t[num1][0]] - a, sz[t[num2][1]] - b) + min(sz[t[num1][1]] - b, sz[t[num2][0]] - a)
	+ max(0, min(a, min(sz[t[num2][1]] - b - (sz[t[num1][0]] - a), sz[t[num1][1]] - b - (sz[t[num2][0]] - a))))
	+ max(0, min(b, min(sz[t[num1][0]] - a - (sz[t[num2][1]] - b), sz[t[num2][0]] - a - (sz[t[num1][1]] - b))));
}
int dp(int num, int d, int x) {
	if (!num) return 0;
	assert(d >= 0);
	// if (d == 0) return sz[num];
	// cout << "! " << d << " " << (x & (1 << d)) << " " << d << " " << num << " " << t[num][0] << " " << t[num][1] << " " << sz[t[num][0]] << " " << sz[t[num][1]] << endl;
	if (x & (1 << d)) return sz[num] - 2 * query(t[num][0], t[num][1], d - 1, x);
	int ls = dp(t[num][0], d - 1, x), rs = dp(t[num][1], d - 1, x);
	if (sz[t[num][0]] < rs) return rs - sz[t[num][0]];
	if (ls > sz[t[num][1]]) return ls - sz[t[num][1]];
	return 0;
}
bool check(int x) {
	int ans = dp(1, 30, x);
	// cout << sz[1] << " " << ans << endl;
	return ans <= ((n / 2) * 2);
}
signed main() {
	read(n);
	F(i, 1, 2 * n) {
		read(a[i]);
		insert(a[i]);
	} int l = 0, r = (1 << 30);
	// cout << check(8) << endl; return 0;
	while (l + 1 < r) {
		int mid = (l + r) >> 1;
		if (check(mid)) l = mid;
		else r = mid;
	} cout << l;
	return 0;
}

提出情報

ジャッジ結果