Submission #696415

#	Time	Username	Problem	Language	Result	Execution time	Memory
696415		finn__	Senior Postmen (BOI14_postmen)	C++17	38 / 100	1081 ms	16748 KiB

postmen

#include <bits/stdc++.h>
using namespace std;

#pragma GCC optimize("O3")
#pragma GCC targe("avx2")

struct Edge
{
    unsigned u, v, i, j, k; // u <-> i, v <-> j;

    Edge(unsigned u_, unsigned v_, unsigned i_, unsigned j_, unsigned k_)
    {
        u = u_, v = v_, i = i_, j = j_, k = k_;
    }
};

vector<vector<Edge>> g;
vector<Edge> edges;
vector<bool> visited;

void delete_edge(Edge e)
{
    swap(g[e.u][e.i], g[e.u].back());
    swap(g[e.v][e.j], g[e.v].back());
    g[e.u].erase(g[e.u].end() - 1);
    g[e.v].erase(g[e.v].end() - 1);

    if (e.i < g[e.u].size())
    {
        g[e.u][e.i].i = e.i;
        edges[g[e.u][e.i].k] = g[e.u][e.i];
        g[g[e.u][e.i].v][g[e.u][e.i].j].j = e.i;
        edges[g[g[e.u][e.i].v][g[e.u][e.i].j].k] = g[g[e.u][e.i].v][g[e.u][e.i].j];
    }
    if (e.j < g[e.v].size())
    {
        g[e.v][e.j].i = e.j;
        edges[g[e.v][e.j].k] = g[e.v][e.j];
        g[g[e.v][e.j].v][g[e.v][e.j].j].j = e.j;
        edges[g[g[e.v][e.j].v][g[e.v][e.j].j].k] = g[g[e.v][e.j].v][g[e.v][e.j].j];
    }
}

unsigned get_next_edge(unsigned u, unsigned p)
{
    for (size_t i = 0; i < g[u].size(); i++)
        if (g[u][i].v != p)
            return i;
}

unsigned find_circuit(unsigned u, unsigned p = -1)
{
    if (visited[u])
        return u;
    visited[u] = 1;

    assert(!g[u].empty());
    Edge e = g[u][get_next_edge(u, p)];
    unsigned x = find_circuit(e.v, u);

    visited[u] = 0;
    if (x != UINT_MAX)
    {
        cout << u + 1 << ' ' << flush;
        delete_edge(edges[e.k]);
        if (u == x)
            x = UINT_MAX;
    }

    return x;
}

int main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);

    size_t n, m;
    cin >> n >> m;

    g = vector<vector<Edge>>(n);
    visited = vector<bool>(n, 0);

    for (size_t i = 0; i < m; i++)
    {
        unsigned u, v;
        cin >> u >> v;
        u--, v--;
        g[u].emplace_back(u, v, g[u].size(), g[v].size(), i);
        g[v].emplace_back(v, u, g[v].size(), g[u].size() - 1, i);
        edges.push_back(g[u].back());
    }

    for (unsigned u = 0; u < n; u++)
    {
        while (!g[u].empty())
        {
            find_circuit(u);
            cout << '\n';
        }
    }
}

Compilation message (stderr)

postmen.cpp:5: warning: ignoring '#pragma GCC targe' [-Wunknown-pragmas]
    5 | #pragma GCC targe("avx2")
      | 
postmen.cpp: In function 'unsigned int get_next_edge(unsigned int, unsigned int)':
postmen.cpp:49:1: warning: control reaches end of non-void function [-Wreturn-type]
   49 | }
      | ^

• Subtask 1: 38 / 38
• Subtask 2: 0 / 17
• Subtask 3: 0 / 45