oj.uz

답안 #749624

# 제출 시각 아이디 문제 언어 결과 실행 시간 메모리
749624 2023-05-28T10:17:17 Z anhduc2701 Alternating Current (BOI18_alternating) C++17
0 / 100
 131 ms 109664 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, 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])
        {
            pq.erase({i, v});
        }
        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);
                }
            }
        }
        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

# 결과 실행 시간 메모리 Grader output
1 Correct 45 ms 98124 KB Output is correct
2 Correct 45 ms 98068 KB Output is correct
3 Correct 47 ms 98200 KB Output is correct
4 Correct 46 ms 98072 KB Output is correct
5 Correct 46 ms 98124 KB Output is correct
6 Correct 45 ms 98148 KB Output is correct
7 Correct 46 ms 98144 KB Output is correct
8 Correct 44 ms 94156 KB Output is correct
9 Correct 47 ms 98132 KB Output is correct
10 Correct 44 ms 94248 KB Output is correct
11 Correct 47 ms 94256 KB Output is correct
12 Correct 46 ms 98168 KB Output is correct
13 Correct 49 ms 94252 KB Output is correct
14 Correct 51 ms 98084 KB Output is correct
15 Correct 45 ms 98152 KB Output is correct
16 Correct 46 ms 98068 KB Output is correct
17 Correct 50 ms 98192 KB Output is correct
18 Incorrect 47 ms 98248 KB no wires in direction 1 between segments 3 and 3
19 Halted 0 ms 0 KB -

Subtask #2
0 / 20.0

# 결과 실행 시간 메모리 Grader output
1 Correct 45 ms 98124 KB Output is correct
2 Correct 45 ms 98068 KB Output is correct
3 Correct 47 ms 98200 KB Output is correct
4 Correct 46 ms 98072 KB Output is correct
5 Correct 46 ms 98124 KB Output is correct
6 Correct 45 ms 98148 KB Output is correct
7 Correct 46 ms 98144 KB Output is correct
8 Correct 44 ms 94156 KB Output is correct
9 Correct 47 ms 98132 KB Output is correct
10 Correct 44 ms 94248 KB Output is correct
11 Correct 47 ms 94256 KB Output is correct
12 Correct 46 ms 98168 KB Output is correct
13 Correct 49 ms 94252 KB Output is correct
14 Correct 51 ms 98084 KB Output is correct
15 Correct 45 ms 98152 KB Output is correct
16 Correct 46 ms 98068 KB Output is correct
17 Correct 50 ms 98192 KB Output is correct
18 Incorrect 47 ms 98248 KB no wires in direction 1 between segments 3 and 3
19 Halted 0 ms 0 KB -

Subtask #3
0 / 22.0

# 결과 실행 시간 메모리 Grader output
1 Correct 45 ms 98124 KB Output is correct
2 Correct 45 ms 98068 KB Output is correct
3 Correct 47 ms 98200 KB Output is correct
4 Correct 46 ms 98072 KB Output is correct
5 Correct 46 ms 98124 KB Output is correct
6 Correct 45 ms 98148 KB Output is correct
7 Correct 46 ms 98144 KB Output is correct
8 Correct 44 ms 94156 KB Output is correct
9 Correct 47 ms 98132 KB Output is correct
10 Correct 44 ms 94248 KB Output is correct
11 Correct 47 ms 94256 KB Output is correct
12 Correct 46 ms 98168 KB Output is correct
13 Correct 49 ms 94252 KB Output is correct
14 Correct 51 ms 98084 KB Output is correct
15 Correct 45 ms 98152 KB Output is correct
16 Correct 46 ms 98068 KB Output is correct
17 Correct 50 ms 98192 KB Output is correct
18 Incorrect 47 ms 98248 KB no wires in direction 1 between segments 3 and 3
19 Halted 0 ms 0 KB -

Subtask #4
0 / 19.0

# 결과 실행 시간 메모리 Grader output
1 Correct 66 ms 102332 KB Output is correct
2 Correct 62 ms 104096 KB Output is correct
3 Correct 55 ms 96820 KB Output is correct
4 Correct 72 ms 105420 KB Output is correct
5 Correct 130 ms 109444 KB Output is correct
6 Correct 74 ms 98176 KB Output is correct
7 Incorrect 131 ms 109664 KB no wires in direction 0 between segments 39205 and 39205
8 Halted 0 ms 0 KB -

Subtask #5
0 / 26.0

# 결과 실행 시간 메모리 Grader output
1 Correct 45 ms 98124 KB Output is correct
2 Correct 45 ms 98068 KB Output is correct
3 Correct 47 ms 98200 KB Output is correct
4 Correct 46 ms 98072 KB Output is correct
5 Correct 46 ms 98124 KB Output is correct
6 Correct 45 ms 98148 KB Output is correct
7 Correct 46 ms 98144 KB Output is correct
8 Correct 44 ms 94156 KB Output is correct
9 Correct 47 ms 98132 KB Output is correct
10 Correct 44 ms 94248 KB Output is correct
11 Correct 47 ms 94256 KB Output is correct
12 Correct 46 ms 98168 KB Output is correct
13 Correct 49 ms 94252 KB Output is correct
14 Correct 51 ms 98084 KB Output is correct
15 Correct 45 ms 98152 KB Output is correct
16 Correct 46 ms 98068 KB Output is correct
17 Correct 50 ms 98192 KB Output is correct
18 Incorrect 47 ms 98248 KB no wires in direction 1 between segments 3 and 3
19 Halted 0 ms 0 KB -