oj.uz

Submission #749649

# Submission time Handle Problem Language Result Execution time Memory
749649 2023-05-28T10:44:58 Z anhduc2701 Alternating Current (BOI18_alternating) C++17
0 / 100
 137 ms 109788 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;
    int id;
    int su = 0;
    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].r > su)
        {
            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])
        {
            if (pq.find({i, v}) != pq.end())
            {
                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;
            pq.erase({id, r});
            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:61:25: warning: suggest parentheses around comparison in operand of '^' [-Wparentheses]
   61 |         else if (col[v] != col[u] ^ 1)
      |                  ~~~~~~~^~~~~~~~~
alternating.cpp: In function 'int main()':
alternating.cpp:108:26: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  108 |                 while (v < check.size() && check[v] <= A[i].r)
      |                        ~~^~~~~~~~~~~~~~
alternating.cpp:118:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  118 |             while (v < check.size())
      |                    ~~^~~~~~~~~~~~~~
alternating.cpp:124:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  124 |             while (v < check.size() && check[v] <= A[i].r)
      |                    ~~^~~~~~~~~~~~~~
alternating.cpp:174:13: warning: unused variable 'id' [-Wunused-variable]
  174 |         int id = 0;
      |             ^~
alternating.cpp:175:13: warning: unused variable 'r' [-Wunused-variable]
  175 |         int r = 0;
      |             ^
alternating.cpp:153:9: warning: unused variable 'id' [-Wunused-variable]
  153 |     int id;
      |         ^~

Subtask #1
0 / 13.0

# Verdict Execution time Memory Grader output
1 Correct 44 ms 98164 KB Output is correct
2 Correct 44 ms 98100 KB Output is correct
3 Correct 45 ms 98124 KB Output is correct
4 Correct 45 ms 98128 KB Output is correct
5 Correct 45 ms 98116 KB Output is correct
6 Correct 45 ms 98140 KB Output is correct
7 Correct 45 ms 98164 KB Output is correct
8 Correct 45 ms 94244 KB Output is correct
9 Correct 49 ms 98104 KB Output is correct
10 Correct 43 ms 94156 KB Output is correct
11 Correct 46 ms 94272 KB Output is correct
12 Correct 45 ms 98100 KB Output is correct
13 Correct 44 ms 94236 KB Output is correct
14 Correct 45 ms 98124 KB Output is correct
15 Correct 55 ms 98128 KB Output is correct
16 Correct 47 ms 98228 KB Output is correct
17 Correct 45 ms 98116 KB Output is correct
18 Incorrect 45 ms 98124 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 44 ms 98164 KB Output is correct
2 Correct 44 ms 98100 KB Output is correct
3 Correct 45 ms 98124 KB Output is correct
4 Correct 45 ms 98128 KB Output is correct
5 Correct 45 ms 98116 KB Output is correct
6 Correct 45 ms 98140 KB Output is correct
7 Correct 45 ms 98164 KB Output is correct
8 Correct 45 ms 94244 KB Output is correct
9 Correct 49 ms 98104 KB Output is correct
10 Correct 43 ms 94156 KB Output is correct
11 Correct 46 ms 94272 KB Output is correct
12 Correct 45 ms 98100 KB Output is correct
13 Correct 44 ms 94236 KB Output is correct
14 Correct 45 ms 98124 KB Output is correct
15 Correct 55 ms 98128 KB Output is correct
16 Correct 47 ms 98228 KB Output is correct
17 Correct 45 ms 98116 KB Output is correct
18 Incorrect 45 ms 98124 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 44 ms 98164 KB Output is correct
2 Correct 44 ms 98100 KB Output is correct
3 Correct 45 ms 98124 KB Output is correct
4 Correct 45 ms 98128 KB Output is correct
5 Correct 45 ms 98116 KB Output is correct
6 Correct 45 ms 98140 KB Output is correct
7 Correct 45 ms 98164 KB Output is correct
8 Correct 45 ms 94244 KB Output is correct
9 Correct 49 ms 98104 KB Output is correct
10 Correct 43 ms 94156 KB Output is correct
11 Correct 46 ms 94272 KB Output is correct
12 Correct 45 ms 98100 KB Output is correct
13 Correct 44 ms 94236 KB Output is correct
14 Correct 45 ms 98124 KB Output is correct
15 Correct 55 ms 98128 KB Output is correct
16 Correct 47 ms 98228 KB Output is correct
17 Correct 45 ms 98116 KB Output is correct
18 Incorrect 45 ms 98124 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 90 ms 107384 KB Output is correct
2 Correct 60 ms 104144 KB Output is correct
3 Correct 55 ms 96716 KB Output is correct
4 Correct 80 ms 105380 KB Output is correct
5 Correct 127 ms 109412 KB Output is correct
6 Correct 69 ms 98224 KB Output is correct
7 Incorrect 137 ms 109788 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 44 ms 98164 KB Output is correct
2 Correct 44 ms 98100 KB Output is correct
3 Correct 45 ms 98124 KB Output is correct
4 Correct 45 ms 98128 KB Output is correct
5 Correct 45 ms 98116 KB Output is correct
6 Correct 45 ms 98140 KB Output is correct
7 Correct 45 ms 98164 KB Output is correct
8 Correct 45 ms 94244 KB Output is correct
9 Correct 49 ms 98104 KB Output is correct
10 Correct 43 ms 94156 KB Output is correct
11 Correct 46 ms 94272 KB Output is correct
12 Correct 45 ms 98100 KB Output is correct
13 Correct 44 ms 94236 KB Output is correct
14 Correct 45 ms 98124 KB Output is correct
15 Correct 55 ms 98128 KB Output is correct
16 Correct 47 ms 98228 KB Output is correct
17 Correct 45 ms 98116 KB Output is correct
18 Incorrect 45 ms 98124 KB no wires in direction 1 between segments 3 and 3
19 Halted 0 ms 0 KB -