#include<bits/stdc++.h>
using namespace::std;
const int N = 1000000 + 5;
int n;
int a[N];
vector<pair<int, int>> parse(vector<int> &v) {
int l = 0;
vector<pair<int, int>> res;
while(l < v.size()) {
int r = l;
while(r < v.size() and v[l] == v[r]) r += 1;
res.emplace_back(v[l], r - l);
l = r;
}
return res;
}
long long get_crossed(vector<pair<int, int>> &a, vector<pair<int, int>> &b, int m) {
int sum_a = 0, sum_b = 0;
for(auto x : a) sum_a += x.second;
for(auto x : b) sum_b += x.second;
long long res = 1ll * sum_a * sum_b;
int at = b.size() - 1;
int sum = 0;
for(auto x : a) {
if(x.first == 0) continue;
int want = m - x.first;
while(at >= 0 and b[at].first >= want) {
sum += b[at].second;
at -= 1;
}
res -= 1ll * x.second * sum;
}
return res;
}
long long get_pairs(vector<pair<int, int>> v, int m) {
vector<int> suffix_sum;
for(int i = 0; i < v.size(); i++) suffix_sum.emplace_back(v[i].second);
suffix_sum.emplace_back(0);
for(int i = (int)suffix_sum.size() - 2; i >= 0; i--) suffix_sum[i] += suffix_sum[i + 1];
long long res = 0;
int at = (int)v.size() - 1;
for(int i = 0; i < v.size(); i++) {
int want = m - v[i].first;
while(at >= 0 and v[at].first >= want) at -= 1;
int to = max(at, i) + 1;
res += 1ll * v[i].second * suffix_sum[to];
if((v[i].first << 1) >= m) res += 1ll * v[i].second * (v[i].second - 1) / 2;
}
return res;
}
long long get_bits(int b, int p) {
vector<int> ones;
vector<int> zeros;
for(int i = 0; i < n; i++) {
if(a[i] & p) ones.emplace_back(a[i] % p);
else zeros.emplace_back(a[i] % p);
}
sort(ones.begin(), ones.end());
sort(zeros.begin(), zeros.end());
vector<pair<int, int>> p_ones = parse(ones), p_zeros = parse(zeros);
long long res = get_crossed(p_ones, p_zeros, p);
if(not ones.empty()) res += get_pairs(p_ones, p);
if(not zeros.empty()) res += get_pairs(p_zeros, p);
return res;
}
int main(){
scanf("%d", &n);
int X = 0, O = 0;
for(int i = 0; i < n; i++) {
scanf("%d", a + i);
X ^= a[i] << 1;
O |= a[i] << 1;
}
for(int b = 0, p = 1; b < 31; b++, p <<= 1) {
long long cnt = get_bits(b, p);
/* long long cnt2 = 0;
for(int i = 0; i < n; i++) {
for(int j = i + 1; j < n; j++) {
if((a[i] + a[j]) & p) cnt2 += 1;
}
}
cerr << p << " -> " << cnt << " vs " << cnt2 << endl;*/
if(cnt & 1) X ^= p;
if(cnt) O |= p;
}
printf("%d\n", X);
return 0;
}
Compilation message
xorsum.cpp: In function 'std::vector<std::pair<int, int> > parse(std::vector<int>&)':
xorsum.cpp:12:10: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
12 | while(l < v.size()) {
| ~~^~~~~~~~~~
xorsum.cpp:14:11: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
14 | while(r < v.size() and v[l] == v[r]) r += 1;
| ~~^~~~~~~~~~
xorsum.cpp: In function 'long long int get_pairs(std::vector<std::pair<int, int> >, int)':
xorsum.cpp:42:19: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
42 | for(int i = 0; i < v.size(); i++) suffix_sum.emplace_back(v[i].second);
| ~~^~~~~~~~~~
xorsum.cpp:47:19: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
47 | for(int i = 0; i < v.size(); i++) {
| ~~^~~~~~~~~~
xorsum.cpp: In function 'int main()':
xorsum.cpp:74:7: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
74 | scanf("%d", &n);
| ~~~~~^~~~~~~~~~
xorsum.cpp:77:8: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
77 | scanf("%d", a + i);
| ~~~~~^~~~~~~~~~~~~
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
8 ms |
344 KB |
Output is correct |
| 2 |
Correct |
7 ms |
600 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
1512 ms |
13520 KB |
Output is correct |
| 2 |
Correct |
1442 ms |
17684 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
1512 ms |
13520 KB |
Output is correct |
| 2 |
Correct |
1442 ms |
17684 KB |
Output is correct |
| 3 |
Execution timed out |
1641 ms |
33580 KB |
Time limit exceeded |
| 4 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
8 ms |
344 KB |
Output is correct |
| 2 |
Correct |
7 ms |
600 KB |
Output is correct |
| 3 |
Correct |
207 ms |
5616 KB |
Output is correct |
| 4 |
Correct |
204 ms |
5580 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
8 ms |
344 KB |
Output is correct |
| 2 |
Correct |
7 ms |
600 KB |
Output is correct |
| 3 |
Correct |
1512 ms |
13520 KB |
Output is correct |
| 4 |
Correct |
1442 ms |
17684 KB |
Output is correct |
| 5 |
Execution timed out |
1641 ms |
33580 KB |
Time limit exceeded |
| 6 |
Halted |
0 ms |
0 KB |
- |
