oj.uz

Submission #749638

# Submission time Handle Problem Language Result Execution time Memory
749638 2023-05-28T10:33:34 Z anhduc2701 Alternating Current (BOI18_alternating) C++17
0 / 100
 150 ms 110056 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 <= m; 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, 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;

            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

# Verdict Execution time Memory Grader output
1 Correct 47 ms 98124 KB Output is correct
2 Correct 43 ms 98164 KB Output is correct
3 Correct 43 ms 98112 KB Output is correct
4 Correct 45 ms 98148 KB Output is correct
5 Correct 44 ms 98100 KB Output is correct
6 Correct 46 ms 98184 KB Output is correct
7 Correct 44 ms 98180 KB Output is correct
8 Correct 43 ms 94228 KB Output is correct
9 Correct 45 ms 98184 KB Output is correct
10 Correct 40 ms 94232 KB Output is correct
11 Correct 44 ms 94268 KB Output is correct
12 Correct 45 ms 98124 KB Output is correct
13 Correct 52 ms 94156 KB Output is correct
14 Correct 47 ms 98120 KB Output is correct
15 Correct 45 ms 98124 KB Output is correct
16 Correct 43 ms 98124 KB Output is correct
17 Correct 45 ms 98204 KB Output is correct
18 Correct 44 ms 98128 KB Output is correct
19 Correct 44 ms 98072 KB Output is correct
20 Correct 50 ms 98080 KB Output is correct
21 Correct 43 ms 98128 KB Output is correct
22 Correct 46 ms 98156 KB Output is correct
23 Correct 48 ms 98156 KB Output is correct
24 Correct 45 ms 98124 KB Output is correct
25 Correct 48 ms 98084 KB Output is correct
26 Correct 44 ms 98144 KB Output is correct
27 Incorrect 45 ms 98152 KB no wires in direction 0 between segments 15 and 15
28 Halted 0 ms 0 KB -

Subtask #2
0 / 20.0

# Verdict Execution time Memory Grader output
1 Correct 47 ms 98124 KB Output is correct
2 Correct 43 ms 98164 KB Output is correct
3 Correct 43 ms 98112 KB Output is correct
4 Correct 45 ms 98148 KB Output is correct
5 Correct 44 ms 98100 KB Output is correct
6 Correct 46 ms 98184 KB Output is correct
7 Correct 44 ms 98180 KB Output is correct
8 Correct 43 ms 94228 KB Output is correct
9 Correct 45 ms 98184 KB Output is correct
10 Correct 40 ms 94232 KB Output is correct
11 Correct 44 ms 94268 KB Output is correct
12 Correct 45 ms 98124 KB Output is correct
13 Correct 52 ms 94156 KB Output is correct
14 Correct 47 ms 98120 KB Output is correct
15 Correct 45 ms 98124 KB Output is correct
16 Correct 43 ms 98124 KB Output is correct
17 Correct 45 ms 98204 KB Output is correct
18 Correct 44 ms 98128 KB Output is correct
19 Correct 44 ms 98072 KB Output is correct
20 Correct 50 ms 98080 KB Output is correct
21 Correct 43 ms 98128 KB Output is correct
22 Correct 46 ms 98156 KB Output is correct
23 Correct 48 ms 98156 KB Output is correct
24 Correct 45 ms 98124 KB Output is correct
25 Correct 48 ms 98084 KB Output is correct
26 Correct 44 ms 98144 KB Output is correct
27 Incorrect 45 ms 98152 KB no wires in direction 0 between segments 15 and 15
28 Halted 0 ms 0 KB -

Subtask #3
0 / 22.0

# Verdict Execution time Memory Grader output
1 Correct 47 ms 98124 KB Output is correct
2 Correct 43 ms 98164 KB Output is correct
3 Correct 43 ms 98112 KB Output is correct
4 Correct 45 ms 98148 KB Output is correct
5 Correct 44 ms 98100 KB Output is correct
6 Correct 46 ms 98184 KB Output is correct
7 Correct 44 ms 98180 KB Output is correct
8 Correct 43 ms 94228 KB Output is correct
9 Correct 45 ms 98184 KB Output is correct
10 Correct 40 ms 94232 KB Output is correct
11 Correct 44 ms 94268 KB Output is correct
12 Correct 45 ms 98124 KB Output is correct
13 Correct 52 ms 94156 KB Output is correct
14 Correct 47 ms 98120 KB Output is correct
15 Correct 45 ms 98124 KB Output is correct
16 Correct 43 ms 98124 KB Output is correct
17 Correct 45 ms 98204 KB Output is correct
18 Correct 44 ms 98128 KB Output is correct
19 Correct 44 ms 98072 KB Output is correct
20 Correct 50 ms 98080 KB Output is correct
21 Correct 43 ms 98128 KB Output is correct
22 Correct 46 ms 98156 KB Output is correct
23 Correct 48 ms 98156 KB Output is correct
24 Correct 45 ms 98124 KB Output is correct
25 Correct 48 ms 98084 KB Output is correct
26 Correct 44 ms 98144 KB Output is correct
27 Incorrect 45 ms 98152 KB no wires in direction 0 between segments 15 and 15
28 Halted 0 ms 0 KB -

Subtask #4
0 / 19.0

# Verdict Execution time Memory Grader output
1 Correct 86 ms 106436 KB Output is correct
2 Correct 56 ms 104100 KB Output is correct
3 Correct 53 ms 96712 KB Output is correct
4 Correct 89 ms 105360 KB Output is correct
5 Correct 122 ms 109484 KB Output is correct
6 Correct 67 ms 98124 KB Output is correct
7 Correct 119 ms 109708 KB Output is correct
8 Correct 57 ms 102600 KB Output is correct
9 Correct 54 ms 101960 KB Output is correct
10 Correct 150 ms 109760 KB Output is correct
11 Correct 122 ms 108476 KB Output is correct
12 Correct 116 ms 110056 KB Output is correct
13 Incorrect 59 ms 104140 KB no wires in direction 0 between segments 100000 and 100000
14 Halted 0 ms 0 KB -

Subtask #5
0 / 26.0

# Verdict Execution time Memory Grader output
1 Correct 47 ms 98124 KB Output is correct
2 Correct 43 ms 98164 KB Output is correct
3 Correct 43 ms 98112 KB Output is correct
4 Correct 45 ms 98148 KB Output is correct
5 Correct 44 ms 98100 KB Output is correct
6 Correct 46 ms 98184 KB Output is correct
7 Correct 44 ms 98180 KB Output is correct
8 Correct 43 ms 94228 KB Output is correct
9 Correct 45 ms 98184 KB Output is correct
10 Correct 40 ms 94232 KB Output is correct
11 Correct 44 ms 94268 KB Output is correct
12 Correct 45 ms 98124 KB Output is correct
13 Correct 52 ms 94156 KB Output is correct
14 Correct 47 ms 98120 KB Output is correct
15 Correct 45 ms 98124 KB Output is correct
16 Correct 43 ms 98124 KB Output is correct
17 Correct 45 ms 98204 KB Output is correct
18 Correct 44 ms 98128 KB Output is correct
19 Correct 44 ms 98072 KB Output is correct
20 Correct 50 ms 98080 KB Output is correct
21 Correct 43 ms 98128 KB Output is correct
22 Correct 46 ms 98156 KB Output is correct
23 Correct 48 ms 98156 KB Output is correct
24 Correct 45 ms 98124 KB Output is correct
25 Correct 48 ms 98084 KB Output is correct
26 Correct 44 ms 98144 KB Output is correct
27 Incorrect 45 ms 98152 KB no wires in direction 0 between segments 15 and 15
28 Halted 0 ms 0 KB -