Submission #98294

#	Time	Username	Problem	Language	Result	Execution time	Memory
98294		keko37	XOR Sum (info1cup17_xorsum)	C++14	45 / 100	1644 ms	42368 KiB

xorsum

#include<bits/stdc++.h>

using namespace std;

typedef long long llint;

const int MAXN = 1000005;

int n;
int a[MAXN], p[MAXN], s[MAXN], sol[35];
vector < pair <int, int> > v;

void update (int k) {
    vector < pair <int, int> > nul, jen;
    for (int i=0; i<n; i++) {
        int val = v[i].first, ind = v[i].second;
        if (a[ind] & (1 << k)) {
            jen.push_back(make_pair(val + (1 << k), ind));
        } else {
            nul.push_back(make_pair(val, ind));
        }
    }
    v.clear();
    for (int i=0; i<nul.size(); i++) v.push_back(nul[i]);
    for (int i=0; i<jen.size(); i++) v.push_back(jen[i]);
}

void ispis () {
    for (int i=0; i<v.size(); i++) {
        cout << v[i].first << " " << v[i].second << "  ";
    }
    cout << endl;
}

void kth (int k) {
    for (int i=0; i<n; i++) {
        if (i > 0) p[i] = p[i-1]; else p[i] = 0;
        int val = v[i].first, ind = v[i].second;
        if (a[ind] & (1 << k)) p[i]++;
    }
    p[n] = p[n-1];
    s[n] = 0;
    for (int i=n-1; i>=0; i--) {
        if (i < n-1) s[i] = s[i+1]; else s[i] = 0;
        int val = v[i].first, ind = v[i].second;
        if (a[ind] & (1 << k)) s[i]++;
    }
    llint res = 0;
    int curr = 0;
    for (int i=n-1; i>=0; i--) {
        while (curr < n && v[i].first + v[curr].first < (1 << k)) curr++;
        int val = v[i].first, ind = v[i].second;
        int tmp;
        if (curr == 0) tmp = 0; else tmp = p[curr-1];
        if (a[ind] & (1 << k)) {
            res += curr - tmp + s[curr];
        } else {
            res += tmp + n - curr - s[curr];
        }
        if ((a[ind] + a[ind]) & (1 << k)) res++;
    }
    sol[k] = (res / 2) % 2;
}

int main () {
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    cin >> n;
    for (int i=1; i<=n; i++) {
        cin >> a[i];
        v.push_back(make_pair(0, i));
    }
    int br = 0;
    for (int i=0; i<=30; i++) {
        kth(i);
        br += sol[i] * (1 << i);
        update(i);
    }
    cout << br << endl;
    return 0;
}

Compilation message (stderr)

xorsum.cpp: In function 'void update(int)':
xorsum.cpp:24:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (int i=0; i<nul.size(); i++) v.push_back(nul[i]);
                   ~^~~~~~~~~~~
xorsum.cpp:25:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (int i=0; i<jen.size(); i++) v.push_back(jen[i]);
                   ~^~~~~~~~~~~
xorsum.cpp: In function 'void ispis()':
xorsum.cpp:29:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (int i=0; i<v.size(); i++) {
                   ~^~~~~~~~~
xorsum.cpp: In function 'void kth(int)':
xorsum.cpp:38:13: warning: unused variable 'val' [-Wunused-variable]
         int val = v[i].first, ind = v[i].second;
             ^~~
xorsum.cpp:45:13: warning: unused variable 'val' [-Wunused-variable]
         int val = v[i].first, ind = v[i].second;
             ^~~
xorsum.cpp:52:13: warning: unused variable 'val' [-Wunused-variable]
         int val = v[i].first, ind = v[i].second;
             ^~~

• Subtask 1: 7 / 7
• Subtask 2: 0 / 11
• Subtask 3: 0 / 21
• Subtask 4: 38 / 38
• Subtask 5: 0 / 23