Submission #571414

#	Time	Username	Problem	Language	Result	Execution time	Memory
571414		BackNoob	XOR (IZhO12_xor)	C++14	100 / 100	197 ms	60424 KiB

xor

#include <bits/stdc++.h>
#define ll long long
#define fi first
#define se second
#define endl '\n'
#define MASK(i) (1LL << (i))
#define ull unsigned long long
#define ld long double
#define pb push_back
#define all(x) (x).begin() , (x).end()
#define BIT(x , i) ((x >> (i)) & 1) 
#define TASK "task"
#define sz(s) (int) (s).size()

using namespace std;
const int mxN = 5e5 + 227;
const int inf = 1e9 + 277;
const int mod = 24211007;
const ll infll = 1e18 + 7;
const int base = 200;
const int LOG = 29;
 
template <typename T1, typename T2> bool minimize(T1 &a, T2 b) {
	if (a > b) {a = b; return true;} return false;
}
template <typename T1, typename T2> bool maximize(T1 &a, T2 b) {
	if (a < b) {a = b; return true;} return false;
}

struct Node{
	Node* child[2];
	int minpos;
	Node()
	{
		child[0] = child[1] = NULL;
		minpos = inf;
	}
};

Node* root = new Node();

void add(int x, int idx)
{
	Node* p = root;
	for(int i = 29; i >= 0; i--) {
		int nxt = BIT(x, i);
		if(p -> child[nxt] == NULL) 
			p -> child[nxt] = new Node();
		p = p -> child[nxt];
		minimize(p -> minpos, idx); 
	}
}

int n;
int k;
int a[mxN];
int pre[mxN];
int timer = 0;
pair<int, int> ans = {-1, -1};

int calc(int x)
{
	// if(timer == 3) cout << x << endl;
	int res = inf;
	Node* p = root;
	for(int j = LOG; j >= 0; j--) {
		if(x & (1 << j)) {
			if(!(k & (1 << j))) {
				if(p -> child[0] != NULL)
					minimize(res, p -> child[0] -> minpos);
				if(p -> child[1] == NULL) return res;
				p = p -> child[1];
				// cout << 1;
			}
			else {
				if(p -> child[0] == NULL) return res;
				p = p -> child[0];
				// cout << 0;
			}
		}
		else {
			if(k & (1 << j)) {
				if(p -> child[1] == NULL) return res;
				p = p -> child[1];
				// cout << 1;
			}
			else {
				if(p -> child[1] != NULL) 
					minimize(res, p -> child[1] -> minpos);
				if(p -> child[0] == NULL) return res;
				p = p -> child[0];
				// cout << 0;
			}
		}
	}
	minimize(res, p -> minpos);

	return res;
}


void solve()
{	
	cin >> n >> k;
	for(int i = 1; i <= n; i++) cin >> a[i];

	for(int i = 1; i <= n; i++) pre[i] = pre[i - 1] ^ a[i];

	add(pre[0], 0);

		
	for(int i = 1; i <= n; i++) {
		++timer;
		int x = calc(pre[i]);
		// cout << endl;
		if(x != inf) {
			if((ans.se - ans.fi + 1) < i - x + 1) {
				ans.fi = x;
				ans.se = i;
			}
			if((ans.se - ans.fi + 1) == i - x + 1) {
				if(ans.fi > x) {
					ans.fi = x;
					ans.se = i;
				}
			}
		}
		add(pre[i], i);
	}

	cout << ans.fi + 1 << ' ' << (ans.se - ans.fi - 1 + 1);
}
 
int main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    //freopen(TASK".in" , "r" , stdin);
    //freopen(TASK".out" , "w" , stdout);
		
    int tc = 1;
    // cin >> tc;
    while(tc--) {
    	solve();
    }
    return 0;
}

• Subtask 1: 100 / 100