#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;
long long long_gcd(long long a, long long b)
{
// cout << "gcd " << a << ' ' << b << '\n';
if(a < b) swap(a, b);
if(b == 0) return a;
return long_gcd(a%b, b);
}
long long long_abs(long long x)
{
if(x >= 0) return x;
return -x;
}
long long long_sign(long long x)
{
if(x > 0) return 1;
return -1;
}
int main()
{
int n;
long long A, B;
cin >> n >> A >> B;
long long period = A / long_gcd(A, B+1);
if (period > 2e18 / B) { // period * B > 2e18
period = 1'000'000'000'000'000'000LL;
} else {
period *= B;
}
// cout << period << '\n';
long long l, r;
long long maxSize = 0;
vector<long long> endpoints;
for(int i = 1; i <= n; i++)
{
cin >> l >> r;
maxSize = max(maxSize, r-l+1);
if(l % period <= r % period)
{
endpoints.push_back(l % period + 1);
endpoints.push_back(-(r % period) - 1 - 1);
}
else
{
endpoints.push_back(l % period + 1);
endpoints.push_back(-period - 1);
endpoints.push_back(0 + 1);
endpoints.push_back(-(r % period) - 1 - 1);
}
}
if(maxSize >= period)
{
cout << period << '\n';
return 0;
}
// for(long long e: endpoints) cout << e << ' ';
// cout << '\n';
sort(endpoints.begin(), endpoints.end(), [] (long long p, long long q)
{
return long_abs(p) < long_abs(q);
});
// for(long long e: endpoints) cout << e << ' ';
// cout << '\n';
long long res = 0;
long long count = 0;
count += long_sign(endpoints[0]);
for(int i = 1; i < endpoints.size(); i++)
{
// cout << count << ' ' << long_abs(endpoints[i]) - long_abs(endpoints[i-1]) << '\n';
if(count > 0) res += long_abs(endpoints[i]) - long_abs(endpoints[i-1]);
count += long_sign(endpoints[i]);
}
cout << res << '\n';
}
Compilation message
strange_device.cpp:37:19: warning: multi-character character constant [-Wmultichar]
37 | period = 1'000'000'000'000'000'000LL;
| ^~~~~
strange_device.cpp:37:27: warning: multi-character character constant [-Wmultichar]
37 | period = 1'000'000'000'000'000'000LL;
| ^~~~~
strange_device.cpp:37:35: warning: multi-character character constant [-Wmultichar]
37 | period = 1'000'000'000'000'000'000LL;
| ^~~~~
strange_device.cpp: In function 'int main()':
strange_device.cpp:37:19: error: expected ';' before '\x303030'
37 | period = 1'000'000'000'000'000'000LL;
| ^~~~~
| ;
strange_device.cpp:94:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
94 | for(int i = 1; i < endpoints.size(); i++)
| ~~^~~~~~~~~~~~~~~~~~
