Submission #97196

#	Time	Username	Problem	Language	Result	Execution time	Memory
97196		caesar2001	XOR Sum (info1cup17_xorsum)	C++14	100 / 100	1568 ms	35704 KiB

xorsum

#include <iostream>
#include <fstream>
#include <algorithm>
#include <vector>
#include <cmath>
#include <utility>

using namespace std;

typedef long long ll;

ll getsol(int n, const vector<pair<int, int>> &v, int l, int r) {
    int i = n, k = n;
    ll ans = 0;
    for(int j = 1; j <= n; j ++) {
        while(i >= 1 && l - v[j].first <= v[i].first)
            i --;
        while(k >= 1 && r - v[j].first <= v[k].first)
            k --;
        if(k >= 1 && v[k].first < r - v[j].first)
            ans += (k - i);
    }

    return ans;
}

int main() {
   //freopen("a.in", "r", stdin);

    ios::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);

    int n;
    cin >> n;
    vector<int> v(n + 1, 0);
    for(int i = 1; i <= n; i ++)
        cin >> v[i];

    vector<pair<int, int>> arr(n + 1, {0, 0});
    for(int i = 1; i <= n; i ++)
        arr[i].second = i;

    ll ans = 0;
    vector<vector<pair<int, int>>> sorted(2, vector<pair<int, int>> (n + 1));
    for(int bit = 0; bit <= 29; bit ++) {
        vector<int> sz(2, 0);
        for(int i = 1; i <= n; i ++)
            sorted[(v[arr[i].second] & (1 << bit)) == (1 << bit)][sz[(v[arr[i].second] & (1 << bit)) == (1 << bit)] ++] = {arr[i].first + (v[arr[i].second] & (1 << bit)), arr[i].second};

        int pos = 0;
        for(int i = 0; i < sz[0]; i ++)
            arr[++ pos] = sorted[0][i];
        for(int i = 0; i < sz[1]; i ++)
            arr[++ pos] = sorted[1][i];

        ll aux = getsol(n, arr, 1 << bit, 1 << (bit + 1)) + getsol(n, arr, (1 << (bit + 1)) + (1 << bit), (1 << (bit + 2)));
        for(int i = 1; i <= n; i ++)
            if((2 * v[i]) & (1 << bit))
                aux ++;

        aux /= 2;
        if(aux % 2 == 1)
            ans += (1 << bit);
    }

    cout << ans;

    return 0;
}

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