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답안 #749652

# 제출 시각 아이디 문제 언어 결과 실행 시간 메모리
749652 2023-05-28T10:47:06 Z anhduc2701 Alternating Current (BOI18_alternating) C++17
0 / 100
 135 ms 110020 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])
        {
            if (pq.find({i, v}) != pq.end())
            {
                pq.erase({i, v});
            }
        }
        for (auto v : st[i])
        {
            if (col[v.se] == -1)
            {

                if (i > v.fi)
                {
                    pq.insert({v.fi + n, v.se});
                }
                else
                {
                    pq.insert({v.fi, v.se});
                    era[v.fi + 1].pb(v.se);
                }
            }
        }
        if (pref2[i] == 0)
        {
            int id = (*pq.rbegin()).se;
            int r = (*pq.rbegin()).fi;
            pq.erase({r, id});
            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 46 ms 98096 KB Output is correct
2 Correct 45 ms 98096 KB Output is correct
3 Correct 46 ms 98076 KB Output is correct
4 Correct 46 ms 98184 KB Output is correct
5 Correct 47 ms 98112 KB Output is correct
6 Correct 48 ms 98124 KB Output is correct
7 Correct 48 ms 98088 KB Output is correct
8 Correct 47 ms 94252 KB Output is correct
9 Correct 46 ms 98136 KB Output is correct
10 Correct 44 ms 94272 KB Output is correct
11 Correct 45 ms 94156 KB Output is correct
12 Correct 50 ms 98124 KB Output is correct
13 Correct 45 ms 94276 KB Output is correct
14 Correct 47 ms 98132 KB Output is correct
15 Correct 47 ms 98188 KB Output is correct
16 Correct 46 ms 98132 KB Output is correct
17 Correct 46 ms 98124 KB Output is correct
18 Correct 47 ms 98124 KB Output is correct
19 Correct 46 ms 98160 KB Output is correct
20 Correct 51 ms 98160 KB Output is correct
21 Correct 47 ms 98188 KB Output is correct
22 Correct 49 ms 98124 KB Output is correct
23 Correct 47 ms 98252 KB Output is correct
24 Correct 46 ms 98188 KB Output is correct
25 Correct 47 ms 98100 KB Output is correct
26 Correct 47 ms 98124 KB Output is correct
27 Incorrect 45 ms 98132 KB no wires in direction 0 between segments 15 and 15
28 Halted 0 ms 0 KB -

Subtask #2
0 / 20.0

# 결과 실행 시간 메모리 Grader output
1 Correct 46 ms 98096 KB Output is correct
2 Correct 45 ms 98096 KB Output is correct
3 Correct 46 ms 98076 KB Output is correct
4 Correct 46 ms 98184 KB Output is correct
5 Correct 47 ms 98112 KB Output is correct
6 Correct 48 ms 98124 KB Output is correct
7 Correct 48 ms 98088 KB Output is correct
8 Correct 47 ms 94252 KB Output is correct
9 Correct 46 ms 98136 KB Output is correct
10 Correct 44 ms 94272 KB Output is correct
11 Correct 45 ms 94156 KB Output is correct
12 Correct 50 ms 98124 KB Output is correct
13 Correct 45 ms 94276 KB Output is correct
14 Correct 47 ms 98132 KB Output is correct
15 Correct 47 ms 98188 KB Output is correct
16 Correct 46 ms 98132 KB Output is correct
17 Correct 46 ms 98124 KB Output is correct
18 Correct 47 ms 98124 KB Output is correct
19 Correct 46 ms 98160 KB Output is correct
20 Correct 51 ms 98160 KB Output is correct
21 Correct 47 ms 98188 KB Output is correct
22 Correct 49 ms 98124 KB Output is correct
23 Correct 47 ms 98252 KB Output is correct
24 Correct 46 ms 98188 KB Output is correct
25 Correct 47 ms 98100 KB Output is correct
26 Correct 47 ms 98124 KB Output is correct
27 Incorrect 45 ms 98132 KB no wires in direction 0 between segments 15 and 15
28 Halted 0 ms 0 KB -

Subtask #3
0 / 22.0

# 결과 실행 시간 메모리 Grader output
1 Correct 46 ms 98096 KB Output is correct
2 Correct 45 ms 98096 KB Output is correct
3 Correct 46 ms 98076 KB Output is correct
4 Correct 46 ms 98184 KB Output is correct
5 Correct 47 ms 98112 KB Output is correct
6 Correct 48 ms 98124 KB Output is correct
7 Correct 48 ms 98088 KB Output is correct
8 Correct 47 ms 94252 KB Output is correct
9 Correct 46 ms 98136 KB Output is correct
10 Correct 44 ms 94272 KB Output is correct
11 Correct 45 ms 94156 KB Output is correct
12 Correct 50 ms 98124 KB Output is correct
13 Correct 45 ms 94276 KB Output is correct
14 Correct 47 ms 98132 KB Output is correct
15 Correct 47 ms 98188 KB Output is correct
16 Correct 46 ms 98132 KB Output is correct
17 Correct 46 ms 98124 KB Output is correct
18 Correct 47 ms 98124 KB Output is correct
19 Correct 46 ms 98160 KB Output is correct
20 Correct 51 ms 98160 KB Output is correct
21 Correct 47 ms 98188 KB Output is correct
22 Correct 49 ms 98124 KB Output is correct
23 Correct 47 ms 98252 KB Output is correct
24 Correct 46 ms 98188 KB Output is correct
25 Correct 47 ms 98100 KB Output is correct
26 Correct 47 ms 98124 KB Output is correct
27 Incorrect 45 ms 98132 KB no wires in direction 0 between segments 15 and 15
28 Halted 0 ms 0 KB -

Subtask #4
0 / 19.0

# 결과 실행 시간 메모리 Grader output
1 Correct 84 ms 106476 KB Output is correct
2 Correct 64 ms 104048 KB Output is correct
3 Correct 55 ms 96748 KB Output is correct
4 Correct 80 ms 105452 KB Output is correct
5 Correct 121 ms 109448 KB Output is correct
6 Correct 71 ms 98116 KB Output is correct
7 Correct 125 ms 109756 KB Output is correct
8 Correct 63 ms 102580 KB Output is correct
9 Correct 55 ms 101968 KB Output is correct
10 Correct 135 ms 109660 KB Output is correct
11 Correct 110 ms 108360 KB Output is correct
12 Correct 110 ms 110020 KB Output is correct
13 Incorrect 60 ms 104080 KB no wires in direction 0 between segments 100000 and 100000
14 Halted 0 ms 0 KB -

Subtask #5
0 / 26.0

# 결과 실행 시간 메모리 Grader output
1 Correct 46 ms 98096 KB Output is correct
2 Correct 45 ms 98096 KB Output is correct
3 Correct 46 ms 98076 KB Output is correct
4 Correct 46 ms 98184 KB Output is correct
5 Correct 47 ms 98112 KB Output is correct
6 Correct 48 ms 98124 KB Output is correct
7 Correct 48 ms 98088 KB Output is correct
8 Correct 47 ms 94252 KB Output is correct
9 Correct 46 ms 98136 KB Output is correct
10 Correct 44 ms 94272 KB Output is correct
11 Correct 45 ms 94156 KB Output is correct
12 Correct 50 ms 98124 KB Output is correct
13 Correct 45 ms 94276 KB Output is correct
14 Correct 47 ms 98132 KB Output is correct
15 Correct 47 ms 98188 KB Output is correct
16 Correct 46 ms 98132 KB Output is correct
17 Correct 46 ms 98124 KB Output is correct
18 Correct 47 ms 98124 KB Output is correct
19 Correct 46 ms 98160 KB Output is correct
20 Correct 51 ms 98160 KB Output is correct
21 Correct 47 ms 98188 KB Output is correct
22 Correct 49 ms 98124 KB Output is correct
23 Correct 47 ms 98252 KB Output is correct
24 Correct 46 ms 98188 KB Output is correct
25 Correct 47 ms 98100 KB Output is correct
26 Correct 47 ms 98124 KB Output is correct
27 Incorrect 45 ms 98132 KB no wires in direction 0 between segments 15 and 15
28 Halted 0 ms 0 KB -