Submission #767640

#	Time	Username	Problem	Language	Result	Execution time	Memory
767640		fanwen	XOR Sum (info1cup17_xorsum)	C++17	100 / 100	443 ms	30736 KiB

xorsum

/**
 *      author : pham van sam 
 *      created : 27 June 2023 (Tuesday)
 **/

#include <bits/stdc++.h>

using namespace std;
using namespace chrono;

#define MASK(x) (1LL << (x))
#define BIT(x, i) (((x) >> (i)) & 1)
#define ALL(x) (x).begin(), (x).end()
#define REP(i, n) for (int i = 0, _n = n; i < _n; ++i)
#define FOR(i, a, b) for (int i = (a), _b = (b); i <= _b; ++i)
#define FORD(i, a, b) for (int i = (a), _b = (b); i >= _b; --i)
#define FORE(it, s) for (__typeof(s.begin()) it = (s).begin(); it != (s).end(); ++it)

template <typename U, typename V> bool maximize(U &A, const V &B) { return (A < B) ? (A = B, true) : false; }
template <typename U, typename V> bool minimize(U &A, const V &B) { return (A > B) ? (A = B, true) : false; }

const int MAXN = 1e6 + 5;
const int LOG = 30;

int N, a[MAXN];

int sum_xor(vector <int> a) {
    int n = (int) a.size();
    int ans = 0;
    REP(bit, LOG) {
        vector <int> bit0, bit1, b(n);
        REP(i, n) (BIT(a[i], bit) ? bit1 : bit0).push_back(a[i]);
        copy(ALL(bit0), a.begin());
        copy(ALL(bit1), a.begin() + (int) bit0.size());
        int j = n, k = n, l = n;
        REP(i, n) b[i] = a[i] & (MASK(bit + 1) - 1);
        REP(i, n) {
            if(j < i) j = i;
            if(k < i) k = i;
            if(l < i) l = i;
            while(j > i && b[j - 1] + b[i] >= MASK(bit)) --j;
            while(k > i && b[k - 1] + b[i] >= MASK(bit + 1)) --k;
            while(l > i && b[l - 1] + b[i] >= MASK(bit) + MASK(bit + 1)) --l;
            if((k - j + n - l) & 1) ans ^= MASK(bit);
        }
    }
    return ans;
}

void process(void) {
    cin >> N;
    REP(i, N) cin >> a[i];
    cout << sum_xor(vector <int> (a, a + N));
}

signed main() {

    #define TASK "TASK"
    if(fopen(TASK".inp", "r")) {
        freopen(TASK".inp", "r", stdin);
        freopen(TASK".out", "w", stdout);
    }

    ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);

    auto start_time = steady_clock::now();
    int test = 1;
    // cin >> test;
    for (int i = 1; i <= test; ++i) {
        process();
        // cout << '\n';
    }

    auto end_time = steady_clock::now();

    cerr << "\nExecution time : " << duration_cast<milliseconds> (end_time - start_time).count() << "[ms]" << endl;

    return (0 ^ 0);
}

Compilation message (stderr)

xorsum.cpp: In function 'int main()':
xorsum.cpp:60:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   60 |         freopen(TASK".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
xorsum.cpp:61:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   61 |         freopen(TASK".out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

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