Submission #62691

#	Time	Username	Problem	Language	Result	Execution time	Memory
62691		eriksuenderhauf	Printed Circuit Board (CEOI12_circuit)	C++11	75 / 100	200 ms	6492 KiB

circuit

#pragma GCC optimize("O3")
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#define enl printf("\n")
#define case(t) printf("Case #%d: ", (t))
#define ni(n) scanf("%d", &(n))
#define nl(n) scanf("%I64d", &(n))
#define nai(a, n) for (int i = 0; i < (n); i++) ni(a[i])
#define nal(a, n) for (int i = 0; i < (n); i++) nl(a[i])
#define pri(n) printf("%d\n", (n))
#define prl(n) printf("%I64d\n", (n))
#define pii pair<int, int>
#define pll pair<long long, long long>
#define vii vector<pii>
#define vi vector<int>
#define pb push_back
#define mp make_pair
#define fi first
#define se second
using namespace std;
using namespace __gnu_pbds;
typedef long long ll;
typedef cc_hash_table<int,int,hash<int>> ht;
const double pi = acos(-1);
const int MOD = 1e9 + 7;
const int INF = 1e9 + 7;
const int MAXN = 1e6 + 5;
const double eps = 1e-9;
pair<pii,int> a[MAXN];
pii b[MAXN];
int n;
bool ans[MAXN], vis[MAXN];

int sgn(pii x, pii y, pii z)
{
    ll ret = 1ll*(ll)(y.fi - x.fi) * (z.se - x.se) - 1ll*(ll)(z.fi - x.fi) * (y.se - x.se);
    if (ret == 0)
        return 0;
    return ret > 0 ? 1 : -1;
}

bool dist(pii lhs, pii rhs)
{
    return lhs.fi+lhs.se < rhs.fi+rhs.se;
}

int nx(int i, int d)
{
    i += d;
    if (i > n)
        i = 1;
    if (i < 1)
        i = n;
    return i;
}

int pr(int i, int d)
{
    i -= d;
    if (i > n)
        i = 1;
    if (i < 1)
        i = n;
    return i;
}
int d = 1;

struct cmp
{
    bool operator()(pair<pii,int> lh, pair<pii,int> rh)
    {
        if (lh == rh)
            return false;
        pii lhs = lh.fi, rhs = rh.fi;
        if (sgn({0,0},lhs,rhs)>=0)
            return (sgn(lhs,b[nx(lh.se,d)],rhs)<=0);
        else
            return (sgn(rhs,b[nx(rh.se,d)],lhs)>0);
    }
};
set<pair<pii,int>, cmp> q;
vi p;

int main()
{
    ni(n);
    int first = 1, last = 1;
    for (int i = 1; i <= n; i++)
    {
        ni(a[i].fi.fi), ni(a[i].fi.se);
        a[i].se = i;
        b[i] = a[i].fi;
        if (i == 1)
            continue;
        int o1 = sgn({0,0},b[first],b[i]);
        if (o1<0||o1==0&&b[i].fi<b[first].fi)
            first = i;
        o1 = sgn({0,0},b[last],b[i]);
        if (o1>0||o1==0&&b[i].fi<b[last].fi)
            last = i;
    }
    int x1 = first + 1; if (x1 > n) x1 = 1;
    int x2 = first - 1; if (x2 == 0) x2 = n;
    if (sgn(b[first], b[x1], b[x2]) < 0)
        d = 1;
    else
        d = -1;
    if (nx(first, d) == last)
    {
        pri(2);
        if (nx(first, 1) < first)
            printf("%d %d\n", nx(first, 1), first);
        else
            printf("%d %d\n", first, nx(first, 1));
        return 0;
    }
    int m = 1;
    for (int i = first; i != nx(last, d); i = nx(i, d))
        p.pb(i);
    sort(p.begin(), p.end(), [](int l, int r) -> bool
         {
            pii lhs = b[l], rhs = b[r];
            int o = sgn({0, 0}, lhs, rhs);
            if (o == 0)
                return dist(lhs, rhs);
            return o > 0 ? true : false;
         });
    ans[first] = 1;
    q.insert({b[first],first});
    vis[first] = 1;
    for (int i = 1; i < p.size(); i++)
    {
        int a1 = p[i];
        int a2 = pr(p[i], d);
        if (vis[a2])
        {
            if ((*q.begin()).se == a2 && sgn({0,0},b[a1],b[p[i-1]]) != 0)
                ans[a1] = 1, m++;
            q.erase(mp(b[a2], a2));
            vis[a2] = false;
        }
        a2 = nx(p[i], d);
        if (sgn({0,0}, b[a1], b[a2]) > 0)
        {
            vis[a1] = 1;
            q.insert(mp(b[a1],a1));
            if ((*q.begin()).se == a1 && sgn({0,0},b[a1],b[p[i-1]]) != 0 && !ans[a1])
                ans[a1] = 1, m++;
        }
    }
    if (!ans[last])
        ans[last] = 1, m++;
    pri(m);
    for (int i = 1; i <= n; i++)
        if (ans[i])
            printf("%d ", i);
    enl;
    return 0;
}

Compilation message (stderr)

circuit.cpp: In function 'int main()':
circuit.cpp:97:24: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
         if (o1<0||o1==0&&b[i].fi<b[first].fi)
                        ^
circuit.cpp:100:24: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
         if (o1>0||o1==0&&b[i].fi<b[last].fi)
                        ^
circuit.cpp:132:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (int i = 1; i < p.size(); i++)
                     ~~^~~~~~~~~~
circuit.cpp:7:20: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
 #define ni(n) scanf("%d", &(n))
               ~~~~~^~~~~~~~~~~~
circuit.cpp:87:5: note: in expansion of macro 'ni'
     ni(n);
     ^~
circuit.cpp:91:23: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         ni(a[i].fi.fi), ni(a[i].fi.se);
                       ^
circuit.cpp:91:23: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]

• Subtask 1: 75 / 100