제출 #389271

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
389271		abc864197532	XOR Sum (info1cup17_xorsum)	C++17	100 / 100	970 ms	21944 KiB

xorsum

#include <bits/stdc++.h>
using namespace std;
#define lli long long int
#define pb push_back
#define eb emplace_back
#define mp make_pair
#define test(x) cout << #x << ' ' << x << endl
#define printv(x) { \
    for (auto a : x) cout << a << ' '; \
    cout << endl; \
}
#define pii pair<int, int>
#define pll pair<lli, lli>
#define X first
#define Y second
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
const int N = 200000, abc = 864197532;

int main () {
    ios::sync_with_stdio(false);
    cin.tie(0);
    int n;
    cin >> n;
    vector <int> a(n);
    for (int i = 0; i < n; ++i) cin >> a[i];
    sort(all(a));
    int ans = 0;
    for (int k = 29; ~k; --k) {
        int p = -1;
        for (int i = 0; i < n; ++i) if (a[i] >= (1 << k + 1)) {
            if (p == -1) p = i;
            a[i] -= (1 << k + 1);
        }
        if (~p) {
            vector <int> b;
            int i, j;
            for (i = 0, j = p; i < p && j < n; ) {
                if (a[i] < a[j]) b.pb(a[i++]);
                else b.pb(a[j++]);
            }
            while (i < p) b.pb(a[i++]);
            while (j < n) b.pb(a[j++]);
            a = b;
        }
        int cnt = 0;
        for (int i = 0, r1 = n, l1 = n, l2 = n; i < n; ++i) {
            while (r1 && (1 << k + 1) - a[i] <= a[r1 - 1]) r1--;
            while (l1 && (1 << k) - a[i] <= a[l1 - 1]) l1--;
            int r = max(r1 - i, 0), l = max(l1 - i, 0);
            cnt ^= (r - l) & 1;
            while (l2 && 3 * (1 << k) - a[i] <= a[l2 - 1]) l2--;
            r = n - i;
            l = max(l2 - i, 0);
            cnt ^= (r - l) & 1;
        }
        /*
         * check k bit
         * mod 2^{k + 1}
         * 1 3
         * count pair 2^k - a <= b < 2^{k + 1} - a
         * 3 * 2^k - a > b
         */
        if (cnt) ans |= 1 << k;
    }
    cout << ans << endl;
}

컴파일 시 표준 에러 (stderr) 메시지

xorsum.cpp: In function 'int main()':
xorsum.cpp:31:57: warning: suggest parentheses around '+' inside '<<' [-Wparentheses]
   31 |         for (int i = 0; i < n; ++i) if (a[i] >= (1 << k + 1)) {
      |                                                       ~~^~~
xorsum.cpp:33:29: warning: suggest parentheses around '+' inside '<<' [-Wparentheses]
   33 |             a[i] -= (1 << k + 1);
      |                           ~~^~~
xorsum.cpp:48:34: warning: suggest parentheses around '+' inside '<<' [-Wparentheses]
   48 |             while (r1 && (1 << k + 1) - a[i] <= a[r1 - 1]) r1--;
      |                                ~~^~~

• Subtask 1: 7 / 7
• Subtask 2: 11 / 11
• Subtask 3: 21 / 21
• Subtask 4: 38 / 38
• Subtask 5: 23 / 23