oj.uz

Submission #749608

# Submission time Handle Problem Language Result Execution time Memory
749608 2023-05-28T09:55:30 Z anhduc2701 Alternating Current (BOI18_alternating) C++17
0 / 100
 131 ms 110276 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});
        }
    }
    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:168:13: warning: unused variable 'id' [-Wunused-variable]
  168 |         int id = 0;
      |             ^~
alternating.cpp:169:13: warning: unused variable 'r' [-Wunused-variable]
  169 |         int r = 0;
      |             ^

Subtask #1
0 / 13.0

# Verdict Execution time Memory Grader output
1 Correct 53 ms 98124 KB Output is correct
2 Correct 51 ms 98184 KB Output is correct
3 Correct 57 ms 98108 KB Output is correct
4 Correct 51 ms 98124 KB Output is correct
5 Correct 49 ms 98132 KB Output is correct
6 Correct 47 ms 98116 KB Output is correct
7 Correct 51 ms 98180 KB Output is correct
8 Correct 47 ms 94252 KB Output is correct
9 Correct 48 ms 98120 KB Output is correct
10 Correct 46 ms 94216 KB Output is correct
11 Correct 52 ms 94236 KB Output is correct
12 Correct 51 ms 98124 KB Output is correct
13 Correct 59 ms 94188 KB Output is correct
14 Correct 46 ms 98096 KB Output is correct
15 Correct 47 ms 98168 KB Output is correct
16 Correct 50 ms 98196 KB Output is correct
17 Correct 61 ms 98108 KB Output is correct
18 Incorrect 47 ms 98128 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 53 ms 98124 KB Output is correct
2 Correct 51 ms 98184 KB Output is correct
3 Correct 57 ms 98108 KB Output is correct
4 Correct 51 ms 98124 KB Output is correct
5 Correct 49 ms 98132 KB Output is correct
6 Correct 47 ms 98116 KB Output is correct
7 Correct 51 ms 98180 KB Output is correct
8 Correct 47 ms 94252 KB Output is correct
9 Correct 48 ms 98120 KB Output is correct
10 Correct 46 ms 94216 KB Output is correct
11 Correct 52 ms 94236 KB Output is correct
12 Correct 51 ms 98124 KB Output is correct
13 Correct 59 ms 94188 KB Output is correct
14 Correct 46 ms 98096 KB Output is correct
15 Correct 47 ms 98168 KB Output is correct
16 Correct 50 ms 98196 KB Output is correct
17 Correct 61 ms 98108 KB Output is correct
18 Incorrect 47 ms 98128 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 53 ms 98124 KB Output is correct
2 Correct 51 ms 98184 KB Output is correct
3 Correct 57 ms 98108 KB Output is correct
4 Correct 51 ms 98124 KB Output is correct
5 Correct 49 ms 98132 KB Output is correct
6 Correct 47 ms 98116 KB Output is correct
7 Correct 51 ms 98180 KB Output is correct
8 Correct 47 ms 94252 KB Output is correct
9 Correct 48 ms 98120 KB Output is correct
10 Correct 46 ms 94216 KB Output is correct
11 Correct 52 ms 94236 KB Output is correct
12 Correct 51 ms 98124 KB Output is correct
13 Correct 59 ms 94188 KB Output is correct
14 Correct 46 ms 98096 KB Output is correct
15 Correct 47 ms 98168 KB Output is correct
16 Correct 50 ms 98196 KB Output is correct
17 Correct 61 ms 98108 KB Output is correct
18 Incorrect 47 ms 98128 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 72 ms 102712 KB Output is correct
2 Correct 74 ms 103744 KB Output is correct
3 Correct 60 ms 97376 KB Output is correct
4 Correct 85 ms 105644 KB Output is correct
5 Correct 131 ms 110212 KB Output is correct
6 Correct 70 ms 99348 KB Output is correct
7 Incorrect 121 ms 110276 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 53 ms 98124 KB Output is correct
2 Correct 51 ms 98184 KB Output is correct
3 Correct 57 ms 98108 KB Output is correct
4 Correct 51 ms 98124 KB Output is correct
5 Correct 49 ms 98132 KB Output is correct
6 Correct 47 ms 98116 KB Output is correct
7 Correct 51 ms 98180 KB Output is correct
8 Correct 47 ms 94252 KB Output is correct
9 Correct 48 ms 98120 KB Output is correct
10 Correct 46 ms 94216 KB Output is correct
11 Correct 52 ms 94236 KB Output is correct
12 Correct 51 ms 98124 KB Output is correct
13 Correct 59 ms 94188 KB Output is correct
14 Correct 46 ms 98096 KB Output is correct
15 Correct 47 ms 98168 KB Output is correct
16 Correct 50 ms 98196 KB Output is correct
17 Correct 61 ms 98108 KB Output is correct
18 Incorrect 47 ms 98128 KB no wires in direction 1 between segments 3 and 3
19 Halted 0 ms 0 KB -