oj.uz

Submission #749613

# Submission time Handle Problem Language Result Execution time Memory
749613 2023-05-28T09:58:24 Z anhduc2701 Alternating Current (BOI18_alternating) C++17
0 / 100
 127 ms 109328 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)
        {
            pref1[A[i].l]++;
            pref1[A[i].r + 1]--;
            if (A[i].l > A[i].r)
                pref1[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++)
    {
        pref1[i] += pref1[i - 1];
        int id = 0;
        int r = 0;
        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);
                }
            }
        }
        for (auto v : era[i])
        {
            pq.erase({i, v});
        }
        if (pref1[i] == 0)
        {
            int id = (*pq.rbegin()).se;
            int r = (*pq.rbegin()).fi;
            col[id] = 1;
            pref1[i + 1]++;
            pref1[r + 1]--;
            if (A[i].l > A[i].r)
            {
                pref1[A[i].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:169:13: warning: unused variable 'id' [-Wunused-variable]
  169 |         int id = 0;
      |             ^~
alternating.cpp:170:13: warning: unused variable 'r' [-Wunused-variable]
  170 |         int r = 0;
      |             ^

Subtask #1
0 / 13.0

# Verdict Execution time Memory Grader output
1 Correct 50 ms 98124 KB Output is correct
2 Correct 45 ms 98136 KB Output is correct
3 Correct 46 ms 98188 KB Output is correct
4 Correct 53 ms 98188 KB Output is correct
5 Correct 50 ms 98252 KB Output is correct
6 Correct 58 ms 98136 KB Output is correct
7 Correct 45 ms 98136 KB Output is correct
8 Correct 47 ms 94180 KB Output is correct
9 Correct 55 ms 98072 KB Output is correct
10 Correct 47 ms 94160 KB Output is correct
11 Correct 46 ms 94156 KB Output is correct
12 Correct 46 ms 98132 KB Output is correct
13 Correct 45 ms 94204 KB Output is correct
14 Correct 47 ms 98076 KB Output is correct
15 Correct 46 ms 98124 KB Output is correct
16 Correct 46 ms 98124 KB Output is correct
17 Correct 47 ms 98072 KB Output is correct
18 Incorrect 48 ms 98188 KB no wires in direction 1 between segments 3 and 3
19 Halted 0 ms 0 KB -

Subtask #2
0 / 20.0

# Verdict Execution time Memory Grader output
1 Correct 50 ms 98124 KB Output is correct
2 Correct 45 ms 98136 KB Output is correct
3 Correct 46 ms 98188 KB Output is correct
4 Correct 53 ms 98188 KB Output is correct
5 Correct 50 ms 98252 KB Output is correct
6 Correct 58 ms 98136 KB Output is correct
7 Correct 45 ms 98136 KB Output is correct
8 Correct 47 ms 94180 KB Output is correct
9 Correct 55 ms 98072 KB Output is correct
10 Correct 47 ms 94160 KB Output is correct
11 Correct 46 ms 94156 KB Output is correct
12 Correct 46 ms 98132 KB Output is correct
13 Correct 45 ms 94204 KB Output is correct
14 Correct 47 ms 98076 KB Output is correct
15 Correct 46 ms 98124 KB Output is correct
16 Correct 46 ms 98124 KB Output is correct
17 Correct 47 ms 98072 KB Output is correct
18 Incorrect 48 ms 98188 KB no wires in direction 1 between segments 3 and 3
19 Halted 0 ms 0 KB -

Subtask #3
0 / 22.0

# Verdict Execution time Memory Grader output
1 Correct 50 ms 98124 KB Output is correct
2 Correct 45 ms 98136 KB Output is correct
3 Correct 46 ms 98188 KB Output is correct
4 Correct 53 ms 98188 KB Output is correct
5 Correct 50 ms 98252 KB Output is correct
6 Correct 58 ms 98136 KB Output is correct
7 Correct 45 ms 98136 KB Output is correct
8 Correct 47 ms 94180 KB Output is correct
9 Correct 55 ms 98072 KB Output is correct
10 Correct 47 ms 94160 KB Output is correct
11 Correct 46 ms 94156 KB Output is correct
12 Correct 46 ms 98132 KB Output is correct
13 Correct 45 ms 94204 KB Output is correct
14 Correct 47 ms 98076 KB Output is correct
15 Correct 46 ms 98124 KB Output is correct
16 Correct 46 ms 98124 KB Output is correct
17 Correct 47 ms 98072 KB Output is correct
18 Incorrect 48 ms 98188 KB no wires in direction 1 between segments 3 and 3
19 Halted 0 ms 0 KB -

Subtask #4
0 / 19.0

# Verdict Execution time Memory Grader output
1 Correct 71 ms 101940 KB Output is correct
2 Correct 63 ms 103644 KB Output is correct
3 Correct 56 ms 96820 KB Output is correct
4 Correct 69 ms 104988 KB Output is correct
5 Correct 123 ms 109004 KB Output is correct
6 Correct 68 ms 98184 KB Output is correct
7 Incorrect 127 ms 109328 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 50 ms 98124 KB Output is correct
2 Correct 45 ms 98136 KB Output is correct
3 Correct 46 ms 98188 KB Output is correct
4 Correct 53 ms 98188 KB Output is correct
5 Correct 50 ms 98252 KB Output is correct
6 Correct 58 ms 98136 KB Output is correct
7 Correct 45 ms 98136 KB Output is correct
8 Correct 47 ms 94180 KB Output is correct
9 Correct 55 ms 98072 KB Output is correct
10 Correct 47 ms 94160 KB Output is correct
11 Correct 46 ms 94156 KB Output is correct
12 Correct 46 ms 98132 KB Output is correct
13 Correct 45 ms 94204 KB Output is correct
14 Correct 47 ms 98076 KB Output is correct
15 Correct 46 ms 98124 KB Output is correct
16 Correct 46 ms 98124 KB Output is correct
17 Correct 47 ms 98072 KB Output is correct
18 Incorrect 48 ms 98188 KB no wires in direction 1 between segments 3 and 3
19 Halted 0 ms 0 KB -