oj.uz

답안 #749620

# 제출 시각 아이디 문제 언어 결과 실행 시간 메모리
749620 2023-05-28T10:10:29 Z anhduc2701 Alternating Current (BOI18_alternating) C++17
0 / 100
 140 ms 109732 KB 
/*
#pragma GCC optimize("Ofast")
#pragma GCC target("avx,avx2,fma")
#pragma GCC optimize("unroll-loops")
*/
#include <bits/stdc++.h>
using namespace std;
#define all(x) x.begin(), x.end()
#define len(x) ll(x.size())
#define eb emplace_back
#define PI acos(-1.0)
#define fi first
#define se second
#define mp make_pair
#define pb push_back
#define MIN(v) *min_element(all(v))
#define MAX(v) *max_element(all(v))
#define BIT(x, i) (1 & ((x) >> (i)))
#define MASK(x) (1LL << (x))
#define task "tnc"
#define rep(i, n) for (int i = 0; i < (n); i++)
#define rep1(i, n) for (int i = 1; i <= (n); i++)
typedef long long ll;
typedef long double ld;
const ll INF = 1e18;
const int maxn = 1e6 + 5;
const int mod = 1e9 + 7;
const int mo = 998244353;
using pi = pair<ll, ll>;
using vi = vector<ll>;
using pii = pair<pair<ll, ll>, ll>;
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
struct seg
{
    int l, r, id;
    seg() {}
    seg(int _l, int _r, int _id)
    {
        l = _l;
        r = _r;
        id = _id;
    }
} A[maxn];
int pref[maxn];
vector<int> G[maxn];
int n, m;
int pref1[maxn];
vector<int> sus[maxn];
int col[maxn];
int ch = 0;
void dfs(int u)
{
    for (auto v : G[u])
    {
        if (col[v] == -1)
        {
            col[v] = col[u] ^ 1;
            dfs(v);
        }
        else if (col[v] != col[u] ^ 1)
        {
            ch = 1;
        }
    }
}
int pref2[maxn];
vector<pair<int, int>> st[maxn];
vector<int> era[maxn];
signed main()
{
    cin.tie(0), cout.tie(0)->sync_with_stdio(0);
    cin >> n >> m;
    for (int i = 1; i <= m; i++)
    {
        int l, r;
        cin >> l >> r;
        st[l].pb({r, i});
        pref[l]++;
        pref[r + 1]--;
        if (l > r)
            pref[1]++;
        A[i] = seg(l, r, i);
    }
    vector<int> check;
    for (int i = 1; i <= n; i++)
    {
        pref[i] += pref[i - 1];
        pref1[i] = pref1[i - 1];
        if (pref[i] == 2)
        {
            check.pb(i);
            pref1[i]++;
        }
        if (pref[i] == 1)
        {
            cout << "impossible\n";
            return 0;
        }
    }
    for (int i = 1; i <= n; i++)
    {
        if (A[i].l <= A[i].r)
        {
            if (pref1[A[i].r] - pref1[A[i].l - 1] > 0)
            {
                int v = lower_bound(check.begin(), check.end(), A[i].l) - check.begin();
                while (v < check.size() && check[v] <= A[i].r)
                {
                    sus[check[v]].pb(i);
                    v++;
                }
            }
        }
        else
        {
            int v = lower_bound(check.begin(), check.end(), A[i].l) - check.begin();
            while (v < check.size())
            {
                sus[check[v]].pb(i);
                v++;
            }
            v = lower_bound(check.begin(), check.end(), 1) - check.begin();
            while (v < check.size() && check[v] <= A[i].r)
            {
                sus[check[v]].pb(i);
                v++;
            }
        }
    }

    for (auto v : check)
    {
        G[sus[v][0]].pb(sus[v][1]);
        G[sus[v][1]].pb(sus[v][0]);
    }
    memset(col, -1, sizeof(col));
    for (int i = 1; i <= m; i++)
    {
        if (G[i].size() && col[i] == -1)
        {
            col[i] = 0;
            dfs(i);
        }
    }
    if (ch == 1)
    {
        cout << "impossible\n";
        return 0;
    }
    set<pair<int, int>> pq;
    for (int i = 1; i <= m; i++)
    {
        if (col[i] == 1)
        {
            pref2[A[i].l]++;
            pref2[A[i].r + 1]--;
            if (A[i].l > A[i].r)
                pref2[1]++;
        }
        if (col[i] == -1 && A[i].l > A[i].r)
        {
            pq.insert({A[i].r, i});
            era[A[i].r + 1].pb(i);
        }
    }
    for (int i = 1; i <= n; i++)
    {
        pref2[i] += pref2[i - 1];

        int id = 0;
        int r = 0;
        for (auto v : era[i])
        {
            pq.erase({i, v});
        }
        for (auto v : st[i])
        {
            if (col[v.se] == -1)
            {
                if (i > v.fi)
                {
                    pq.insert({v.fi + n, i});
                }
                else
                {
                    pq.insert({v.fi, i});
                    era[v.fi + 1].pb(i);
                }
            }
        }
        if (pref2[i] == 0)
        {
            int id = (*pq.rbegin()).se;
            int r = (*pq.rbegin()).fi;

            col[id] = 1;
            pref2[i + 1]++;
            pref2[r + 1]--;
            if (A[id].l > A[id].r)
            {
                pref2[A[id].l]++;
            }
        }
    }
    for (int i = 1; i <= m; i++)
    {
        if (col[i] == 1)
        {
            cout << 1;
        }
        else
        {
            cout << 0;
        }
    }
}

Compilation message

alternating.cpp: In function 'void dfs(int)':
alternating.cpp:60:25: warning: suggest parentheses around comparison in operand of '^' [-Wparentheses]
   60 |         else if (col[v] != col[u] ^ 1)
      |                  ~~~~~~~^~~~~~~~~
alternating.cpp: In function 'int main()':
alternating.cpp:107:26: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  107 |                 while (v < check.size() && check[v] <= A[i].r)
      |                        ~~^~~~~~~~~~~~~~
alternating.cpp:117:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  117 |             while (v < check.size())
      |                    ~~^~~~~~~~~~~~~~
alternating.cpp:123:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  123 |             while (v < check.size() && check[v] <= A[i].r)
      |                    ~~^~~~~~~~~~~~~~
alternating.cpp:170:13: warning: unused variable 'id' [-Wunused-variable]
  170 |         int id = 0;
      |             ^~
alternating.cpp:171:13: warning: unused variable 'r' [-Wunused-variable]
  171 |         int r = 0;
      |             ^

Subtask #1
0 / 13.0

# 결과 실행 시간 메모리 Grader output
1 Correct 44 ms 98160 KB Output is correct
2 Correct 46 ms 98104 KB Output is correct
3 Correct 47 ms 98144 KB Output is correct
4 Correct 47 ms 98252 KB Output is correct
5 Correct 45 ms 98108 KB Output is correct
6 Correct 45 ms 98172 KB Output is correct
7 Correct 45 ms 98156 KB Output is correct
8 Correct 44 ms 94160 KB Output is correct
9 Correct 45 ms 98172 KB Output is correct
10 Correct 47 ms 94156 KB Output is correct
11 Correct 44 ms 94212 KB Output is correct
12 Correct 46 ms 98184 KB Output is correct
13 Correct 44 ms 94220 KB Output is correct
14 Correct 52 ms 98200 KB Output is correct
15 Correct 51 ms 98084 KB Output is correct
16 Correct 49 ms 98176 KB Output is correct
17 Correct 45 ms 98124 KB Output is correct
18 Incorrect 45 ms 98120 KB no wires in direction 1 between segments 3 and 3
19 Halted 0 ms 0 KB -

Subtask #2
0 / 20.0

# 결과 실행 시간 메모리 Grader output
1 Correct 44 ms 98160 KB Output is correct
2 Correct 46 ms 98104 KB Output is correct
3 Correct 47 ms 98144 KB Output is correct
4 Correct 47 ms 98252 KB Output is correct
5 Correct 45 ms 98108 KB Output is correct
6 Correct 45 ms 98172 KB Output is correct
7 Correct 45 ms 98156 KB Output is correct
8 Correct 44 ms 94160 KB Output is correct
9 Correct 45 ms 98172 KB Output is correct
10 Correct 47 ms 94156 KB Output is correct
11 Correct 44 ms 94212 KB Output is correct
12 Correct 46 ms 98184 KB Output is correct
13 Correct 44 ms 94220 KB Output is correct
14 Correct 52 ms 98200 KB Output is correct
15 Correct 51 ms 98084 KB Output is correct
16 Correct 49 ms 98176 KB Output is correct
17 Correct 45 ms 98124 KB Output is correct
18 Incorrect 45 ms 98120 KB no wires in direction 1 between segments 3 and 3
19 Halted 0 ms 0 KB -

Subtask #3
0 / 22.0

# 결과 실행 시간 메모리 Grader output
1 Correct 44 ms 98160 KB Output is correct
2 Correct 46 ms 98104 KB Output is correct
3 Correct 47 ms 98144 KB Output is correct
4 Correct 47 ms 98252 KB Output is correct
5 Correct 45 ms 98108 KB Output is correct
6 Correct 45 ms 98172 KB Output is correct
7 Correct 45 ms 98156 KB Output is correct
8 Correct 44 ms 94160 KB Output is correct
9 Correct 45 ms 98172 KB Output is correct
10 Correct 47 ms 94156 KB Output is correct
11 Correct 44 ms 94212 KB Output is correct
12 Correct 46 ms 98184 KB Output is correct
13 Correct 44 ms 94220 KB Output is correct
14 Correct 52 ms 98200 KB Output is correct
15 Correct 51 ms 98084 KB Output is correct
16 Correct 49 ms 98176 KB Output is correct
17 Correct 45 ms 98124 KB Output is correct
18 Incorrect 45 ms 98120 KB no wires in direction 1 between segments 3 and 3
19 Halted 0 ms 0 KB -

Subtask #4
0 / 19.0

# 결과 실행 시간 메모리 Grader output
1 Correct 66 ms 102308 KB Output is correct
2 Correct 75 ms 104140 KB Output is correct
3 Correct 55 ms 96784 KB Output is correct
4 Correct 83 ms 105484 KB Output is correct
5 Correct 140 ms 109420 KB Output is correct
6 Correct 81 ms 98268 KB Output is correct
7 Incorrect 116 ms 109732 KB no wires in direction 0 between segments 1174 and 1174
8 Halted 0 ms 0 KB -

Subtask #5
0 / 26.0

# 결과 실행 시간 메모리 Grader output
1 Correct 44 ms 98160 KB Output is correct
2 Correct 46 ms 98104 KB Output is correct
3 Correct 47 ms 98144 KB Output is correct
4 Correct 47 ms 98252 KB Output is correct
5 Correct 45 ms 98108 KB Output is correct
6 Correct 45 ms 98172 KB Output is correct
7 Correct 45 ms 98156 KB Output is correct
8 Correct 44 ms 94160 KB Output is correct
9 Correct 45 ms 98172 KB Output is correct
10 Correct 47 ms 94156 KB Output is correct
11 Correct 44 ms 94212 KB Output is correct
12 Correct 46 ms 98184 KB Output is correct
13 Correct 44 ms 94220 KB Output is correct
14 Correct 52 ms 98200 KB Output is correct
15 Correct 51 ms 98084 KB Output is correct
16 Correct 49 ms 98176 KB Output is correct
17 Correct 45 ms 98124 KB Output is correct
18 Incorrect 45 ms 98120 KB no wires in direction 1 between segments 3 and 3
19 Halted 0 ms 0 KB -