#include<bits/stdc++.h>
using namespace std;
#pragma GCC optimize("O3")
#define tof_io ios_base::sync_with_stdio(false);cin.tie(0) , cout.tie(0);
#define double long double
#define int long long
#define pb push_back
#define all(x) x.begin(),x.end()
#define endl '\n'
#define sz(x) x.size()
//const int mod = 998244353; //998244353 1e9+7 1e9+9
const int N = 5e3 + 23;
const int lg = 23;
const int inf = 1e9;
int fac[N];
int inv[N];
//int dnt_pow (int a, int b, int md = mod){int ans = 1; while(b){if(b&1){ans = (a*ans)%md;}a = (a*a)%md;b >>= 1;}return ans ;}
//void dnt_bld (){fac[0] = 1; inv[0] = dnt_pow(fac[0],mod-2) ;for(int i = 1 ; i < N ; i++) {fac[i] = (fac[i-1] * i) % mod;inv[i] = dnt_pow( fac[i] , mod-2);}}
//int dnt_ncr (int r,int n){if(r>n) return 0; return fac[n] * inv[r] % mod * inv[n-r] % mod;}
void add (set<pair<int, int>>& st, int l, int r)
{
auto it = st.lower_bound({l, 0}), tmp = it;
if (it != st.begin() && (--tmp)->second >= l)
{
l = tmp->first;
r = max(r, tmp->second);
st.erase(tmp);
}
while (it != st.end())
{
if (r >= it->first)
{
r = max(r, it->second);
it = st.erase(it);
}
else break;
}
st.insert({l, r});
}
int32_t main ()
{
int n, a, b;
cin >> n >> a >> b;
int mod;
if (a / gcd(a, b+1) > inf / b) mod = inf;
else mod = a / gcd(a, b+1) * b;
set<pair<int, int>> st;
while (n--)
{
int l, r;
cin >> l >> r;
if (r-l+1 >= mod)
{
cout << mod << endl;
return 0;
}
if (l % mod > r % mod)
{
add(st, 0, r % mod);
add(st, l % mod, mod-1);
} else add(st, l % mod, r % mod);
}
int ans = 0;
for (auto& [l, r] : st) ans += r-l+1;
cout << ans ;
return 0;
}
Compilation message
strange_device.cpp: In function 'int32_t main()':
strange_device.cpp:48:10: error: 'gcd' was not declared in this scope
48 | if (a / gcd(a, b+1) > inf / b) mod = inf;
| ^~~
strange_device.cpp:67:13: warning: structured bindings only available with '-std=c++17' or '-std=gnu++17'
67 | for (auto& [l, r] : st) ans += r-l+1;
| ^
