Submission #1294647

#	Time	Username	Problem	Language	Result	Execution time	Memory
1294647		7ak	Strange Device (APIO19_strange_device)	C++20	100 / 100	307 ms	32712 KiB

strange_device

#include <cstdio>
#include <vector>
#include <algorithm>

using namespace std;

typedef long long ll;
typedef pair<ll,ll> ii;

int n;
ll a, b, t;

vector<ii> p;

const ll MAXT = 1e18+18;

int main(){
    scanf("%d%lld%lld", &n, &a, &b);
    p.resize(n);
    for(int i=0;i<n;++i){
        scanf("%lld%lld", &p[i].first, &p[i].second);
    }
    a = a/__gcd(a, b+1);
    if(b>MAXT/a){ //every t has a distinct pair
        ll sol = 0;
        for(auto i:p){
            sol += i.second-i.first+1;
        }
        printf("%lld\n", sol);
    }else{ //pairs repeat every t moments
        ll t = a*b;
        vector<ii> p2;
        for(auto i:p){
            if(i.first/t==i.second/t){
                p2.push_back(ii(i.first%t, i.second%t));
            }else if(i.first/t+1==i.second/t){
                p2.push_back(ii(i.first%t, t-1));
                p2.push_back(ii(0, i.second%t));
            }else{
                printf("%lld", t);
                return 0;
            }
        }
        sort(p2.begin(), p2.end());
        ll s, e, sol=0;
        for(int i=0, j=0;i<p2.size();i=j){
            s=p2[i].first;e=p2[i].second;
            for(;j<p2.size() && p2[j].first<=e;++j){
                e=max(e, p2[j].second);
            }
            sol+=e-s+1;
        }
        printf("%lld\n", sol);
    }

}

Compilation message (stderr)

strange_device.cpp: In function 'int main()':
strange_device.cpp:18:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   18 |     scanf("%d%lld%lld", &n, &a, &b);
      |     ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~
strange_device.cpp:21:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   21 |         scanf("%lld%lld", &p[i].first, &p[i].second);
      |         ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 10 / 10
• Subtask 2: 5 / 5
• Subtask 3: 5 / 5
• Subtask 4: 5 / 5
• Subtask 5: 5 / 5
• Subtask 6: 20 / 20
• Subtask 7: 20 / 20
• Subtask 8: 30 / 30