oj.uz

Submission #749723

# Submission time Handle Problem Language Result Execution time Memory
749723 2023-05-28T12:09:23 Z anhduc2701 Alternating Current (BOI18_alternating) C++17
0 / 100
 143 ms 110280 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 51 ms 98104 KB Output is correct
2 Correct 50 ms 98200 KB Output is correct
3 Correct 53 ms 98096 KB Output is correct
4 Correct 60 ms 98080 KB Output is correct
5 Correct 56 ms 98112 KB Output is correct
6 Correct 48 ms 98192 KB Output is correct
7 Correct 47 ms 98112 KB Output is correct
8 Correct 56 ms 94160 KB Output is correct
9 Correct 52 ms 98188 KB Output is correct
10 Correct 57 ms 94244 KB Output is correct
11 Correct 58 ms 94232 KB Output is correct
12 Correct 46 ms 98124 KB Output is correct
13 Correct 60 ms 94240 KB Output is correct
14 Correct 65 ms 98096 KB Output is correct
15 Correct 60 ms 98156 KB Output is correct
16 Correct 57 ms 98124 KB Output is correct
17 Correct 49 ms 98108 KB Output is correct
18 Incorrect 52 ms 98084 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 51 ms 98104 KB Output is correct
2 Correct 50 ms 98200 KB Output is correct
3 Correct 53 ms 98096 KB Output is correct
4 Correct 60 ms 98080 KB Output is correct
5 Correct 56 ms 98112 KB Output is correct
6 Correct 48 ms 98192 KB Output is correct
7 Correct 47 ms 98112 KB Output is correct
8 Correct 56 ms 94160 KB Output is correct
9 Correct 52 ms 98188 KB Output is correct
10 Correct 57 ms 94244 KB Output is correct
11 Correct 58 ms 94232 KB Output is correct
12 Correct 46 ms 98124 KB Output is correct
13 Correct 60 ms 94240 KB Output is correct
14 Correct 65 ms 98096 KB Output is correct
15 Correct 60 ms 98156 KB Output is correct
16 Correct 57 ms 98124 KB Output is correct
17 Correct 49 ms 98108 KB Output is correct
18 Incorrect 52 ms 98084 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 51 ms 98104 KB Output is correct
2 Correct 50 ms 98200 KB Output is correct
3 Correct 53 ms 98096 KB Output is correct
4 Correct 60 ms 98080 KB Output is correct
5 Correct 56 ms 98112 KB Output is correct
6 Correct 48 ms 98192 KB Output is correct
7 Correct 47 ms 98112 KB Output is correct
8 Correct 56 ms 94160 KB Output is correct
9 Correct 52 ms 98188 KB Output is correct
10 Correct 57 ms 94244 KB Output is correct
11 Correct 58 ms 94232 KB Output is correct
12 Correct 46 ms 98124 KB Output is correct
13 Correct 60 ms 94240 KB Output is correct
14 Correct 65 ms 98096 KB Output is correct
15 Correct 60 ms 98156 KB Output is correct
16 Correct 57 ms 98124 KB Output is correct
17 Correct 49 ms 98108 KB Output is correct
18 Incorrect 52 ms 98084 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 73 ms 102788 KB Output is correct
2 Correct 73 ms 103668 KB Output is correct
3 Correct 69 ms 97392 KB Output is correct
4 Correct 96 ms 105572 KB Output is correct
5 Correct 143 ms 110028 KB Output is correct
6 Correct 82 ms 99232 KB Output is correct
7 Incorrect 126 ms 110280 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 51 ms 98104 KB Output is correct
2 Correct 50 ms 98200 KB Output is correct
3 Correct 53 ms 98096 KB Output is correct
4 Correct 60 ms 98080 KB Output is correct
5 Correct 56 ms 98112 KB Output is correct
6 Correct 48 ms 98192 KB Output is correct
7 Correct 47 ms 98112 KB Output is correct
8 Correct 56 ms 94160 KB Output is correct
9 Correct 52 ms 98188 KB Output is correct
10 Correct 57 ms 94244 KB Output is correct
11 Correct 58 ms 94232 KB Output is correct
12 Correct 46 ms 98124 KB Output is correct
13 Correct 60 ms 94240 KB Output is correct
14 Correct 65 ms 98096 KB Output is correct
15 Correct 60 ms 98156 KB Output is correct
16 Correct 57 ms 98124 KB Output is correct
17 Correct 49 ms 98108 KB Output is correct
18 Incorrect 52 ms 98084 KB no wires in direction 1 between segments 3 and 3
19 Halted 0 ms 0 KB -