oj.uz

Submission #749631

# Submission time Handle Problem Language Result Execution time Memory
749631 2023-05-28T10:23:24 Z anhduc2701 Alternating Current (BOI18_alternating) C++17
0 / 100
 120 ms 109768 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, A[i].id});
            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.begin()).se;
            int r = (*pq.begin()).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 46 ms 98212 KB Output is correct
2 Correct 44 ms 98084 KB Output is correct
3 Correct 46 ms 98144 KB Output is correct
4 Correct 44 ms 98164 KB Output is correct
5 Correct 44 ms 98072 KB Output is correct
6 Correct 43 ms 98180 KB Output is correct
7 Correct 49 ms 98192 KB Output is correct
8 Correct 42 ms 94216 KB Output is correct
9 Correct 43 ms 98124 KB Output is correct
10 Correct 43 ms 94156 KB Output is correct
11 Correct 45 ms 94240 KB Output is correct
12 Correct 49 ms 98124 KB Output is correct
13 Correct 42 ms 94204 KB Output is correct
14 Correct 43 ms 98152 KB Output is correct
15 Correct 45 ms 98132 KB Output is correct
16 Correct 45 ms 98172 KB Output is correct
17 Correct 52 ms 98176 KB Output is correct
18 Correct 48 ms 98180 KB Output is correct
19 Correct 45 ms 98112 KB Output is correct
20 Correct 46 ms 98192 KB Output is correct
21 Correct 45 ms 98072 KB Output is correct
22 Correct 44 ms 98112 KB Output is correct
23 Correct 45 ms 98104 KB Output is correct
24 Correct 44 ms 98076 KB Output is correct
25 Correct 47 ms 98168 KB Output is correct
26 Correct 46 ms 98124 KB Output is correct
27 Incorrect 46 ms 98192 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 46 ms 98212 KB Output is correct
2 Correct 44 ms 98084 KB Output is correct
3 Correct 46 ms 98144 KB Output is correct
4 Correct 44 ms 98164 KB Output is correct
5 Correct 44 ms 98072 KB Output is correct
6 Correct 43 ms 98180 KB Output is correct
7 Correct 49 ms 98192 KB Output is correct
8 Correct 42 ms 94216 KB Output is correct
9 Correct 43 ms 98124 KB Output is correct
10 Correct 43 ms 94156 KB Output is correct
11 Correct 45 ms 94240 KB Output is correct
12 Correct 49 ms 98124 KB Output is correct
13 Correct 42 ms 94204 KB Output is correct
14 Correct 43 ms 98152 KB Output is correct
15 Correct 45 ms 98132 KB Output is correct
16 Correct 45 ms 98172 KB Output is correct
17 Correct 52 ms 98176 KB Output is correct
18 Correct 48 ms 98180 KB Output is correct
19 Correct 45 ms 98112 KB Output is correct
20 Correct 46 ms 98192 KB Output is correct
21 Correct 45 ms 98072 KB Output is correct
22 Correct 44 ms 98112 KB Output is correct
23 Correct 45 ms 98104 KB Output is correct
24 Correct 44 ms 98076 KB Output is correct
25 Correct 47 ms 98168 KB Output is correct
26 Correct 46 ms 98124 KB Output is correct
27 Incorrect 46 ms 98192 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 46 ms 98212 KB Output is correct
2 Correct 44 ms 98084 KB Output is correct
3 Correct 46 ms 98144 KB Output is correct
4 Correct 44 ms 98164 KB Output is correct
5 Correct 44 ms 98072 KB Output is correct
6 Correct 43 ms 98180 KB Output is correct
7 Correct 49 ms 98192 KB Output is correct
8 Correct 42 ms 94216 KB Output is correct
9 Correct 43 ms 98124 KB Output is correct
10 Correct 43 ms 94156 KB Output is correct
11 Correct 45 ms 94240 KB Output is correct
12 Correct 49 ms 98124 KB Output is correct
13 Correct 42 ms 94204 KB Output is correct
14 Correct 43 ms 98152 KB Output is correct
15 Correct 45 ms 98132 KB Output is correct
16 Correct 45 ms 98172 KB Output is correct
17 Correct 52 ms 98176 KB Output is correct
18 Correct 48 ms 98180 KB Output is correct
19 Correct 45 ms 98112 KB Output is correct
20 Correct 46 ms 98192 KB Output is correct
21 Correct 45 ms 98072 KB Output is correct
22 Correct 44 ms 98112 KB Output is correct
23 Correct 45 ms 98104 KB Output is correct
24 Correct 44 ms 98076 KB Output is correct
25 Correct 47 ms 98168 KB Output is correct
26 Correct 46 ms 98124 KB Output is correct
27 Incorrect 46 ms 98192 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 87 ms 106420 KB Output is correct
2 Correct 67 ms 104232 KB Output is correct
3 Correct 56 ms 96744 KB Output is correct
4 Correct 74 ms 105476 KB Output is correct
5 Correct 120 ms 109388 KB Output is correct
6 Correct 67 ms 98192 KB Output is correct
7 Incorrect 114 ms 109768 KB no wires in direction 1 between segments 762 and 762
8 Halted 0 ms 0 KB -

Subtask #5
0 / 26.0

# Verdict Execution time Memory Grader output
1 Correct 46 ms 98212 KB Output is correct
2 Correct 44 ms 98084 KB Output is correct
3 Correct 46 ms 98144 KB Output is correct
4 Correct 44 ms 98164 KB Output is correct
5 Correct 44 ms 98072 KB Output is correct
6 Correct 43 ms 98180 KB Output is correct
7 Correct 49 ms 98192 KB Output is correct
8 Correct 42 ms 94216 KB Output is correct
9 Correct 43 ms 98124 KB Output is correct
10 Correct 43 ms 94156 KB Output is correct
11 Correct 45 ms 94240 KB Output is correct
12 Correct 49 ms 98124 KB Output is correct
13 Correct 42 ms 94204 KB Output is correct
14 Correct 43 ms 98152 KB Output is correct
15 Correct 45 ms 98132 KB Output is correct
16 Correct 45 ms 98172 KB Output is correct
17 Correct 52 ms 98176 KB Output is correct
18 Correct 48 ms 98180 KB Output is correct
19 Correct 45 ms 98112 KB Output is correct
20 Correct 46 ms 98192 KB Output is correct
21 Correct 45 ms 98072 KB Output is correct
22 Correct 44 ms 98112 KB Output is correct
23 Correct 45 ms 98104 KB Output is correct
24 Correct 44 ms 98076 KB Output is correct
25 Correct 47 ms 98168 KB Output is correct
26 Correct 46 ms 98124 KB Output is correct
27 Incorrect 46 ms 98192 KB no wires in direction 0 between segments 15 and 15
28 Halted 0 ms 0 KB -