Submission #1034561

#	Time	Username	Problem	Language	Result	Execution time	Memory
1034561		andrei_iorgulescu	Strange Device (APIO19_strange_device)	C++14	100 / 100	932 ms	69868 KiB

strange_device

#include <bits/stdc++.h>

using namespace std;

#define int long long

int n,A,B;
int l[1000005],r[1000005];

signed main()
{
    cin >> n >> A >> B;
    for (int i = 1; i <= n; i++)
        cin >> l[i] >> r[i];
    __int128 AA = A, BB = B;
    __int128 FF = AA * BB / __gcd(AA,BB + 1);
    if (FF > r[n])
    {
        int sumlen = 0;
        for (int i = 1; i <= n; i++)
            sumlen += r[i] - l[i] + 1;
        cout << sumlen;
    }
    else
    {
        int F = FF;
        for (int i = 1; i <= n; i++)
        {
            if (r[i] - l[i] + 1 >= F)
            {
                cout << F;
                return 0;
            }
        }
        vector<pair<int,int>> h;
        for (int i = 1; i <= n; i++)
        {
            if (r[i] % F >= l[i] % F)
                h.push_back({l[i] % F,r[i] % F});
            else
                h.push_back({0,r[i] % F}),h.push_back({l[i] % F,F - 1});
        }
        sort(h.begin(),h.end());
        int ans = F;
        int rmax = -1;
        if (h.back().second != F - 1)
            ans -= F - 1 - h.back().second;
        for (auto it : h)
        {
            if (it.first > rmax + 1)
                ans -= (it.first - rmax - 1);
            rmax = max(rmax,it.second);
        }
        cout << ans;
    }
    return 0;
}

///cate resturi modulo A * B / gcd(A,B + 1) gasesc?

• 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