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Submission #672054

# Submission time Handle Problem Language Result Execution time Memory
672054 2022-12-14T16:35:33 Z LittleCube Alternating Current (BOI18_alternating) C++17
0 / 100
 83 ms 10384 KB 
#include <bits/stdc++.h>
#define ll long long
#define pii pair<int, int>
#define pll pair<ll, ll>
#define F first
#define S second
using namespace std;

int N, M, ans[100005], a[100005], b[100005];
vector<int> E[100005];

struct segTree
{
    int seg[400005], lazy[400005];

    int getval(int i)
    {
        return seg[i] + lazy[i];
    }

    void push(int i)
    {
        lazy[i << 1] += lazy[i];
        lazy[i << 1 | 1] += lazy[i];
        seg[i] += lazy[i];
        lazy[i] = 0;
    }

    void pull(int i)
    {
        seg[i] = min(getval(i << 1), getval(i << 1 | 1));
    }

    void modify(int mL, int mR, int val, int i = 1, int L = 1, int R = N)
    {
        if (mL <= L && R <= mR)
            lazy[i] += val;
        else if (R < mL || mR < L)
            return;
        else
        {
            int mid = (L + R) / 2;
            push(i);
            modify(mL, mR, val, i << 1, L, mid);
            modify(mL, mR, val, i << 1 | 1, mid + 1, R);
            pull(i);
        }
    }

    int query(int qL, int qR, int i = 1, int L = 1, int R = N)
    {
        if (qL <= L && R <= qR)
            return getval(i);
        else if (R < qL || qR < L)
            return 1e9;
        else
        {
            int mid = (L + R) / 2;
            push(i);
            return min(query(qL, qR, i << 1, L, mid), query(qL, qR, i << 1 | 1, mid + 1, R));
        }
    }
} seg;

bool dfs(int u)
{
    bool r = 1;
    for (int v : E[u])
        if (ans[v] == 0)
        {
            ans[v] = ans[u] ^ 3;
            r &= dfs(v);
        }
        else
            r &= (ans[u] ^ ans[v]) == 3;
    return r;
}

signed main()
{
    ios::sync_with_stdio(0), cin.tie(0);
    cin >> N >> M;
    set<int> sweep;
    vector<pii> event;
    for (int i = 1; i <= M; i++)
    {
        cin >> a[i] >> b[i];
        if (b[i] < a[i])
        {
            sweep.insert(i);
            event.emplace_back(pii(b[i] + 1, -i));
            event.emplace_back(pii(a[i], i));
        }
        else
        {
            event.emplace_back(pii(a[i], i));
            event.emplace_back(pii(b[i] + 1, -i));
        }
    }
    sort(event.begin(), event.end());
    for (int i = 1, j = 0; i <= N; i++)
    {
        while (j < event.size() && event[j].F == i)
        {
            auto [t, k] = event[j];
            if (k > 0)
                sweep.insert(k);
            else
                sweep.erase(-k);
            j++;
        }
        if (sweep.size() == 1)
        {
            cout << "impossible\n";
            return 0;
        }
        else if (sweep.size() == 2)
        {
            int u = *sweep.begin(), v = *next(sweep.begin());
            E[u].emplace_back(v);
            E[v].emplace_back(u);
        }
    }
    for (int i = 1; i <= M; i++)
        if (ans[i] == 0 && !E[i].empty())
        {
            ans[i] = 1;
            if (!dfs(i))
            {
                cout << "impossible\n";
                return 0;
            }
        }
    for (int i = 1; i <= M; i++)
    {
        if (ans[i] <= 1)
        {
            if (b[i] < a[i])
            {
                seg.modify(a[i], N, 1);
                seg.modify(1, b[i], 1);
            }
            else
                seg.modify(a[i], b[i], 1);
        }
    }
    for (int i = 1; i <= M; i++)
        if (ans[i] == 0)
        {
            int rem = 0;
            if (b[i] < a[i])
                rem = min(seg.query(a[i], N), seg.query(1, b[i]));
            else
                rem = seg.query(a[i], b[i]);

            assert(rem > 0);
            if (rem >= 2)
            {
                ans[i] = 2;
                if (b[i] < a[i])
                {
                    seg.modify(a[i], N, -1);
                    seg.modify(1, b[i], -1);
                }
                else
                    seg.modify(a[i], b[i], -1);
            }
            else
                ans[i] = 1;
        }
    assert(seg.query(N, N) > 0);
    for (int i = 1; i <= M; i++)
        cout << ans[i] - 1;
    cout << '\n';
}
/*
5 6
1 3
2 4
3 5
4 1
5 2
1 3
*/

Compilation message

alternating.cpp: In function 'int main()':
alternating.cpp:103:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  103 |         while (j < event.size() && event[j].F == i)
      |                ~~^~~~~~~~~~~~~~

Subtask #1
0 / 13.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 2644 KB Output is correct
2 Correct 2 ms 2644 KB Output is correct
3 Correct 2 ms 2644 KB Output is correct
4 Correct 2 ms 2644 KB Output is correct
5 Correct 2 ms 2644 KB Output is correct
6 Correct 2 ms 2644 KB Output is correct
7 Correct 2 ms 2644 KB Output is correct
8 Correct 2 ms 2644 KB Output is correct
9 Correct 2 ms 2644 KB Output is correct
10 Correct 1 ms 2644 KB Output is correct
11 Correct 2 ms 2644 KB Output is correct
12 Correct 1 ms 2644 KB Output is correct
13 Correct 2 ms 2644 KB Output is correct
14 Correct 1 ms 2644 KB Output is correct
15 Correct 1 ms 2644 KB Output is correct
16 Correct 1 ms 2644 KB Output is correct
17 Correct 1 ms 2644 KB Output is correct
18 Correct 1 ms 2644 KB Output is correct
19 Correct 2 ms 2644 KB Output is correct
20 Correct 1 ms 2644 KB Output is correct
21 Correct 2 ms 2644 KB Output is correct
22 Correct 1 ms 2644 KB Output is correct
23 Correct 1 ms 2644 KB Output is correct
24 Correct 1 ms 2644 KB Output is correct
25 Correct 1 ms 2644 KB Output is correct
26 Correct 2 ms 2644 KB Output is correct
27 Runtime error 4 ms 5208 KB Execution killed with signal 6
28 Halted 0 ms 0 KB -

Subtask #2
0 / 20.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 2644 KB Output is correct
2 Correct 2 ms 2644 KB Output is correct
3 Correct 2 ms 2644 KB Output is correct
4 Correct 2 ms 2644 KB Output is correct
5 Correct 2 ms 2644 KB Output is correct
6 Correct 2 ms 2644 KB Output is correct
7 Correct 2 ms 2644 KB Output is correct
8 Correct 2 ms 2644 KB Output is correct
9 Correct 2 ms 2644 KB Output is correct
10 Correct 1 ms 2644 KB Output is correct
11 Correct 2 ms 2644 KB Output is correct
12 Correct 1 ms 2644 KB Output is correct
13 Correct 2 ms 2644 KB Output is correct
14 Correct 1 ms 2644 KB Output is correct
15 Correct 1 ms 2644 KB Output is correct
16 Correct 1 ms 2644 KB Output is correct
17 Correct 1 ms 2644 KB Output is correct
18 Correct 1 ms 2644 KB Output is correct
19 Correct 2 ms 2644 KB Output is correct
20 Correct 1 ms 2644 KB Output is correct
21 Correct 2 ms 2644 KB Output is correct
22 Correct 1 ms 2644 KB Output is correct
23 Correct 1 ms 2644 KB Output is correct
24 Correct 1 ms 2644 KB Output is correct
25 Correct 1 ms 2644 KB Output is correct
26 Correct 2 ms 2644 KB Output is correct
27 Runtime error 4 ms 5208 KB Execution killed with signal 6
28 Halted 0 ms 0 KB -

Subtask #3
0 / 22.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 2644 KB Output is correct
2 Correct 2 ms 2644 KB Output is correct
3 Correct 2 ms 2644 KB Output is correct
4 Correct 2 ms 2644 KB Output is correct
5 Correct 2 ms 2644 KB Output is correct
6 Correct 2 ms 2644 KB Output is correct
7 Correct 2 ms 2644 KB Output is correct
8 Correct 2 ms 2644 KB Output is correct
9 Correct 2 ms 2644 KB Output is correct
10 Correct 1 ms 2644 KB Output is correct
11 Correct 2 ms 2644 KB Output is correct
12 Correct 1 ms 2644 KB Output is correct
13 Correct 2 ms 2644 KB Output is correct
14 Correct 1 ms 2644 KB Output is correct
15 Correct 1 ms 2644 KB Output is correct
16 Correct 1 ms 2644 KB Output is correct
17 Correct 1 ms 2644 KB Output is correct
18 Correct 1 ms 2644 KB Output is correct
19 Correct 2 ms 2644 KB Output is correct
20 Correct 1 ms 2644 KB Output is correct
21 Correct 2 ms 2644 KB Output is correct
22 Correct 1 ms 2644 KB Output is correct
23 Correct 1 ms 2644 KB Output is correct
24 Correct 1 ms 2644 KB Output is correct
25 Correct 1 ms 2644 KB Output is correct
26 Correct 2 ms 2644 KB Output is correct
27 Runtime error 4 ms 5208 KB Execution killed with signal 6
28 Halted 0 ms 0 KB -

Subtask #4
0 / 19.0

# Verdict Execution time Memory Grader output
1 Correct 48 ms 10216 KB Output is correct
2 Correct 3 ms 3664 KB Output is correct
3 Correct 13 ms 4052 KB Output is correct
4 Correct 76 ms 7940 KB Output is correct
5 Correct 69 ms 9948 KB Output is correct
6 Correct 38 ms 5328 KB Output is correct
7 Correct 70 ms 9776 KB Output is correct
8 Correct 7 ms 4948 KB Output is correct
9 Correct 4 ms 4820 KB Output is correct
10 Correct 76 ms 10384 KB Output is correct
11 Correct 61 ms 8896 KB Output is correct
12 Correct 83 ms 9948 KB Output is correct
13 Runtime error 9 ms 7676 KB Execution killed with signal 6
14 Halted 0 ms 0 KB -

Subtask #5
0 / 26.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 2644 KB Output is correct
2 Correct 2 ms 2644 KB Output is correct
3 Correct 2 ms 2644 KB Output is correct
4 Correct 2 ms 2644 KB Output is correct
5 Correct 2 ms 2644 KB Output is correct
6 Correct 2 ms 2644 KB Output is correct
7 Correct 2 ms 2644 KB Output is correct
8 Correct 2 ms 2644 KB Output is correct
9 Correct 2 ms 2644 KB Output is correct
10 Correct 1 ms 2644 KB Output is correct
11 Correct 2 ms 2644 KB Output is correct
12 Correct 1 ms 2644 KB Output is correct
13 Correct 2 ms 2644 KB Output is correct
14 Correct 1 ms 2644 KB Output is correct
15 Correct 1 ms 2644 KB Output is correct
16 Correct 1 ms 2644 KB Output is correct
17 Correct 1 ms 2644 KB Output is correct
18 Correct 1 ms 2644 KB Output is correct
19 Correct 2 ms 2644 KB Output is correct
20 Correct 1 ms 2644 KB Output is correct
21 Correct 2 ms 2644 KB Output is correct
22 Correct 1 ms 2644 KB Output is correct
23 Correct 1 ms 2644 KB Output is correct
24 Correct 1 ms 2644 KB Output is correct
25 Correct 1 ms 2644 KB Output is correct
26 Correct 2 ms 2644 KB Output is correct
27 Runtime error 4 ms 5208 KB Execution killed with signal 6
28 Halted 0 ms 0 KB -