oj.uz

답안 #581257

# 제출 시각 아이디 문제 언어 결과 실행 시간 메모리
581257 2022-06-22T12:32:34 Z Lobo Alternating Current (BOI18_alternating) C++17
0 / 100
 73 ms 11124 KB 
#include<bits/stdc++.h>
using namespace std;

const long long inf = (long long) 1e18 + 10;
const int inf1 = (int) 1e9 + 10;
#define int long long
#define dbl long double
#define endl '\n'
#define sc second
#define fr first
#define mp make_pair
#define pb push_back
#define all(x) x.begin(), x.end()

const int maxn = 2e5+10;

int n, m, pai[maxn], ps[maxn], ans[maxn];

int find(int v) {
    if(pai[v] == v) return v;
    return pai[v] = find(pai[v]);
}

bool cmp(pair<pair<int,int>,int> a, pair<pair<int,int>,int> b) {
    if(a.fr.fr == b.fr.fr) {
        return a.fr.sc > b.fr.sc;
    }
    return a.fr.fr < b.fr.fr;
}

void solve() {
    cin >> n >> m;
    vector<pair<pair<int,int>,int>> segs;
    vector<pair<int,int>> vec;
    for(int i = 0; i < m; i++) {
        int a,b; cin >> a >> b;
        vec.pb(mp(a,b));
        pai[i] = i;
        if(b >= a) {
            ps[a]++;
            ps[b+1]--;
            ps[a+n]++;
            ps[b+n+1]--;

            segs.pb(mp(mp(a,b),i));
            segs.pb(mp(mp(a+n,b+n),i));
        }
        else {
            ps[a]++;
            ps[b+n+1]--;
            ps[1]++;
            ps[b+1]--;
            ps[a+n]++;
            ps[2*n+1]--;
            segs.pb(mp(mp(a,b+n),i));
        }
    }

    sort(all(segs),cmp); //menor L, maior R
    priority_queue<pair<pair<int,int>,int>,vector<pair<pair<int,int>,int>>,greater<pair<pair<int,int>,int>>> pq;
    for(auto X : segs) {
        int l = X.fr.fr;
        int r = X.fr.sc;
        int id = X.sc;
        // cout << l << " " << r << " " << id << endl;
        while(pq.size() && pq.top().fr.sc < r) pq.pop();
        if(pq.size() && pq.top().fr.fr <= l) {
            pai[id] = pq.top().sc;
        }
        else {
            pq.push(mp(mp(l,r),id));
        }
    }

    segs.clear();
    for(int i = 0; i < m; i++) {
        // find(i);
        // cout << i << " " << pai[i] << endl;
        if(pai[i] == i) {
            int a = vec[i].fr;
            int b = vec[i].sc;
            if(b >= a) {
                segs.pb(mp(mp(a,b),i));
            }
            else {
                segs.pb(mp(mp(a,b+n),i));
            }
        }
    }
    sort(all(segs));

    bool ok = true;
    for(int i = 1; i <= 2*n; i++) {
        ps[i]+=ps[i-1];
        if(ps[i] < 2) ok = false;
    }
    if(!ok) {
        cout << "impossible" << endl;
        return;
    }

    for(auto x : segs) {
        // cout << x.fr.fr << " " << x.fr.sc << " " << x.sc << endl;
    }
    if((((int) segs.size())&1) == 0) {
        for(int i = 0; i < segs.size(); i++) {
            int id = segs[i].sc;
            ans[id] = i&1;
        }
        for(int i = 0; i < m; i++) {
            if(pai[i] == i) continue;
            ans[i] = ans[pai[i]]^1;
        }

        for(int i = 0; i < m; i++) {
            cout << ans[i];
        }cout << endl;
    }
    else {
        if(segs.size() == 1) {
            ans[segs[0].sc] = 1;
            for(int i = 0; i < m; i++) {
                cout << ans[i];
            }cout << endl;
            return;
        }
        bool ok = false;
        for(int i = 0; i+1 < segs.size(); i++) {
            int l1 = segs[i].fr.fr;
            int r1 = segs[i].fr.sc;
            int l2 = segs[i+1].fr.fr;
            int r2 = segs[i+1].fr.sc;

            //a area coberta por dois é l2 até r1
            int l = l2;
            int r = r1;
            bool ok1 = true;
            for(int i = l; i <= r; i++) {
                if(ps[i] < 3) {
                    ok1 = false;
                    break;
                }
            }
            if(ok1) {
                int cnt = 0;
                for(int j = i; j < segs.size(); j++) {
                    int id = segs[j].sc;
                    ans[id]=cnt;
                    cnt^=1;
                }
                for(int j = 0; j < i; j++) {
                    int id = segs[j].sc;
                    ans[id]=cnt;
                    cnt^=1;
                }
                ok = true;
                break;
            }
        }
        if(ok == false) {
            //ultimo com o primeiro
            int l1 = segs.back().fr.fr;
            int r1 = segs.back().fr.sc;
            int l2 = segs[0].fr.fr+n;
            int r2 = segs[0].fr.sc+n;
            int l = l2;
            int r = r1;
            bool ok1 = true;
            for(int i = l; i <= r; i++) {
                if(ps[i] < 3) {
                    ok1 = false;
                    break;
                }
            }
            if(ok1) {
                int cnt = 0;
                int i = 0;
                for(int j = i; j < segs.size(); j++) {
                    int id = segs[j].sc;
                    ans[id]=cnt;
                    cnt^=1;
                }
                for(int j = 0; j < i; j++) {
                    int id = segs[j].sc;
                    ans[id]=cnt;
                    cnt^=1;
                }
                ok = true;
            }

        }
        if(ok == false) {
            cout << "impossible" << endl;
            return;
        }
        for(int i = 0; i < m; i++) {
            if(pai[i] == i) continue;
            ans[i] = ans[pai[i]]^1;
        }
        for(int i = 0; i < m; i++) {
            cout << ans[i];
        }cout << endl;

    }

}

int32_t main() {
    ios::sync_with_stdio(false); cin.tie(0);

    // freopen("in.in", "r", stdin);
    // freopen("out.out", "w", stdout);
    int tt = 1;
    // cin >> tt;
    while(tt--) {
        solve();
    }

}

Compilation message

alternating.cpp: In function 'void solve()':
alternating.cpp:102:14: warning: variable 'x' set but not used [-Wunused-but-set-variable]
  102 |     for(auto x : segs) {
      |              ^
alternating.cpp:106:26: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<std::pair<std::pair<long long int, long long int>, long long int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  106 |         for(int i = 0; i < segs.size(); i++) {
      |                        ~~^~~~~~~~~~~~~
alternating.cpp:128:28: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<std::pair<std::pair<long long int, long long int>, long long int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  128 |         for(int i = 0; i+1 < segs.size(); i++) {
      |                        ~~~~^~~~~~~~~~~~~
alternating.cpp:146:34: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<std::pair<std::pair<long long int, long long int>, long long int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  146 |                 for(int j = i; j < segs.size(); j++) {
      |                                ~~^~~~~~~~~~~~~
alternating.cpp:129:17: warning: unused variable 'l1' [-Wunused-variable]
  129 |             int l1 = segs[i].fr.fr;
      |                 ^~
alternating.cpp:132:17: warning: unused variable 'r2' [-Wunused-variable]
  132 |             int r2 = segs[i+1].fr.sc;
      |                 ^~
alternating.cpp:178:34: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<std::pair<std::pair<long long int, long long int>, long long int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  178 |                 for(int j = i; j < segs.size(); j++) {
      |                                ~~^~~~~~~~~~~~~
alternating.cpp:162:17: warning: unused variable 'l1' [-Wunused-variable]
  162 |             int l1 = segs.back().fr.fr;
      |                 ^~
alternating.cpp:165:17: warning: unused variable 'r2' [-Wunused-variable]
  165 |             int r2 = segs[0].fr.sc+n;
      |                 ^~

Subtask #1
0 / 13.0

# 결과 실행 시간 메모리 Grader output
1 Correct 1 ms 340 KB Output is correct
2 Correct 1 ms 328 KB Output is correct
3 Correct 1 ms 340 KB Output is correct
4 Incorrect 1 ms 324 KB no wires in direction 1 between segments 12 and 13
5 Halted 0 ms 0 KB -

Subtask #2
0 / 20.0

# 결과 실행 시간 메모리 Grader output
1 Correct 1 ms 340 KB Output is correct
2 Correct 1 ms 328 KB Output is correct
3 Correct 1 ms 340 KB Output is correct
4 Incorrect 1 ms 324 KB no wires in direction 1 between segments 12 and 13
5 Halted 0 ms 0 KB -

Subtask #3
0 / 22.0

# 결과 실행 시간 메모리 Grader output
1 Correct 1 ms 340 KB Output is correct
2 Correct 1 ms 328 KB Output is correct
3 Correct 1 ms 340 KB Output is correct
4 Incorrect 1 ms 324 KB no wires in direction 1 between segments 12 and 13
5 Halted 0 ms 0 KB -

Subtask #4
0 / 19.0

# 결과 실행 시간 메모리 Grader output
1 Correct 49 ms 10784 KB Output is correct
2 Correct 2 ms 1876 KB Output is correct
3 Correct 24 ms 6084 KB Output is correct
4 Correct 25 ms 6248 KB Output is correct
5 Correct 70 ms 10832 KB Output is correct
6 Correct 73 ms 10712 KB Output is correct
7 Correct 57 ms 10740 KB Output is correct
8 Correct 3 ms 2260 KB Output is correct
9 Correct 2 ms 1872 KB Output is correct
10 Correct 67 ms 11124 KB Output is correct
11 Correct 62 ms 10712 KB Output is correct
12 Correct 60 ms 10820 KB Output is correct
13 Correct 2 ms 1876 KB Output is correct
14 Correct 2 ms 1876 KB Output is correct
15 Incorrect 61 ms 10708 KB no wires in direction 1 between segments 1 and 1
16 Halted 0 ms 0 KB -

Subtask #5
0 / 26.0

# 결과 실행 시간 메모리 Grader output
1 Correct 1 ms 340 KB Output is correct
2 Correct 1 ms 328 KB Output is correct
3 Correct 1 ms 340 KB Output is correct
4 Incorrect 1 ms 324 KB no wires in direction 1 between segments 12 and 13
5 Halted 0 ms 0 KB -