Submission #249969

#	Time	Username	Problem	Language	Result	Execution time	Memory
249969		jeqcho	Strange Device (APIO19_strange_device)	C++17	10 / 100	562 ms	26512 KiB

strange_device

#include <bits/stdc++.h>
using namespace std;

typedef long long ll;
typedef pair<int,int> pii;
typedef vector<int> vi;
typedef vector<pair<int,int>> vpi;

#define FOR(i,a,b) for (int i = (a); i < (b); ++i)
#define F0R(i,a) FOR(i,0,a)
#define ROF(i,a,b) for (int i = (b)-1; i >= (a); --i)
#define R0F(i,a) ROF(i,0,a)
#define trav(a,x) for (auto& a: x)

#define pb push_back
#define rsz resize
#define sz(x) int(x.size())
#define all(x) begin(x), end(x)
#define f first
#define s second

ll A,B;

ll gcd(ll a, ll b)
{
    // O((log n)^2)
    if (b == 0)
        return a;
    return gcd(b, a % b);
}

ll lcm(ll a, ll b)
{
    return (a * b) / gcd(a, b);
}

int main()
{
    ios_base::sync_with_stdio(0); cin.tie(0);
    int n;
    cin>>n>>A>>B;
    ll l,r;
    ll lcm1 = lcm(B+1,A);
    ll q = lcm1 / (B+1);
    ll maxlen = q*B;
    vector<pair<ll,ll>> segments;
    F0R(i,n)
    {
        cin>>l>>r;
        if(r-l+1 >= maxlen)
        {
            cout<<maxlen<<'\n';
            return 0;
        }
        l %= maxlen;
        r %= maxlen;
        if(r<l)
        {
            segments.pb({0,r});
            segments.pb({l,maxlen-1});
        }
        else segments.pb({l,r});
    }
    sort(all(segments));
    bool init=0;
    ll ldex,rdex;
    ll ans=0;
    pair<ll,ll> seg;
    F0R(i,sz(segments)+1)
    {
        if(i==sz(segments))
        {
            ans += rdex-ldex+1;
            break;
        }
        seg = segments[i];
        if(!init)
        {
            ldex=seg.f;
            rdex=seg.s;
            init=1;
        }
        else if(seg.f==ldex)
        {
            rdex = seg.s;
        }
        else
        {
            // seg.f > ldex
            if(seg.f <= rdex)
            {
                rdex = seg.s;
            }
            else
            {
                ans += rdex-ldex+1;
                ldex=seg.f;
                rdex=seg.s;
            }
        }
    }
    cout<<ans<<endl;
    return 0;
}

Compilation message (stderr)

strange_device.cpp: In function 'int main()':
strange_device.cpp:73:24: warning: 'rdex' may be used uninitialized in this function [-Wmaybe-uninitialized]
             ans += rdex-ldex+1;
                    ~~~~^~~~~
strange_device.cpp:73:24: warning: 'ldex' may be used uninitialized in this function [-Wmaybe-uninitialized]

• Subtask 1: 0 / 10
• Subtask 2: 0 / 5
• Subtask 3: 0 / 5
• Subtask 4: 5 / 5
• Subtask 5: 5 / 5
• Subtask 6: 0 / 20
• Subtask 7: 0 / 20
• Subtask 8: 0 / 30