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Submission #1115565

# Submission time Handle Problem Language Result Execution time Memory
1115565 2024-11-20T16:02:29 Z vjudge1 One-Way Streets (CEOI17_oneway) C++17
100 / 100
 117 ms 83136 KB 
#include <bits/stdc++.h>

using namespace std;

#define TASK "oneway"
#define REP(i, n) for(int i = 1; i <= n; i++)
#define FOR(i, a, b) for(auto i = a; i <= b; i++)
#define FORD(i, a, b) for(auto i = a; i >= b; i--)
template<class T> bool maximize(T& a, T b) { if(a < b) return a = b, 1; return 0; }
template<class T> bool minimize(T& a, T b) { if(a > b) return a = b, 1; return 0; }

using ii = pair<int, int>;
#define fi first
#define se second

const int N = (int)1e6 + 7;
int n, m, q;
vector<ii> adj[N];
vector<int> G[N], unUsed;
ii edge[N];
int isLeft[N], isRight[N], status[N]; // 1 B, 2 L, 3 R
int group[N];
ii way[N];

void Read()
{
    cin >> n >> m;
    REP(i, m)
    {
        int u, v;
        cin >> u >> v;
        edge[i] = {u, v};
        adj[u].push_back({v, i});
        adj[v].push_back({u, i});
    }
    cin >> q;
    REP(i, q)
        cin >> way[i].fi >> way[i].se;
}

int low[N], num[N], timeVis = 0, numSCC = 0;

stack<int> st;

void Tarjan(int u, int p = -1)
{
    low[u] = num[u] = ++timeVis;
    st.push(u);
    for(auto [v, id] : adj[u])
    {
        if(id == p)
            continue;
        if(low[v])
            minimize(low[u], num[v]);
        else
        {
            Tarjan(v, id);
            minimize(low[u], low[v]);
        }
    }
    if(low[u] == num[u])
    {
        int v;
        group[u] = ++numSCC;
        do
        {
            v = st.top();
            st.pop();
            group[v] = numSCC;
        } while(v != u);
    }

}

const int LOG = 31 - __builtin_clz(N);
int par[N][LOG + 3], h[N];
void LCA_Precompute(int u, int p = -1)
{
    for(auto v : G[u])
    {
        if(v == p)
            continue;
        par[v][0] = u;
        h[v] = h[u] + 1;
        REP(i, LOG)
            par[v][i] = par[par[v][i - 1]][i - 1];
        LCA_Precompute(v, u);
    }
}

int LCA(int u, int v)
{
    if(h[u] != h[v])
    {
        if(h[u] < h[v]) swap(u, v);
        int diff = h[u] - h[v];
        FOR(i, 0, LOG)
            if(diff >> i & 1) u = par[u][i];
    }
    if(u == v) return u;
    FORD(i, LOG, 0)
    {
        if(par[u][i] == par[v][i])
            continue;
        u = par[u][i];
        v = par[v][i];
    }
    return par[u][0];
}

int BinaryLifting(int u, int diff)
{
    FOR(i, 0, LOG)
    {
        if(diff >> i & 1) u = par[u][i];
    }
    return u;
}

void DFS(int u, int p = -1)
{
    for(auto v : G[u])
    {
        if(v == p)
            continue;
        DFS(v, u);
        isLeft[u] += isLeft[v];
        isRight[u] += isRight[v];
    }
}

void Solve()
{
    vector<int> root;
    REP(i, n)
    {
        if(!group[i])
        {
            Tarjan(i);
            root.push_back(group[i]);
        }
    }
    REP(i, m)
    {
        auto [u, v] = edge[i];
        u = group[u];
        v = group[v];
        if(u == v) status[i] = 1;
        else
        {
            unUsed.push_back(i);
            if(u > v) swap(u, v);
            G[u].push_back(v);
            G[v].push_back(u);
        }
    }
    for(auto node : root)
    {
        LCA_Precompute(node);
    }
    REP(i, q)
    {
        int u = group[way[i].fi];
        int v = group[way[i].se];
        int p = LCA(u, v);
        isLeft[u]++;
        isLeft[p]--;
        isRight[p]--;
        isRight[v]++;
    }
    for(auto node : root)
        DFS(node);
    for(auto i : unUsed)
    {
        auto [u, v] = edge[i];
        u = group[u];
        v = group[v];
        if(status[i]) continue;
        if(h[u] > h[v])
        {
            swap(u, v);
            if(isLeft[v] == isRight[v]) status[i] = 1;
            else if(isLeft[v] > isRight[v]) status[i] = 3;
            else status[i] = 2;
        }
        else
        {
            if(isLeft[v] == isRight[v]) status[i] = 1;
            else if(isLeft[v] > isRight[v]) status[i] = 2;
            else status[i] = 3;
        }
    }
    REP(i, m)
    {
        if(status[i] == 2) cout << 'L';
        else if(status[i] == 3) cout << 'R';
        else
            cout << 'B';
    }
}

signed main()
{
    cin.tie(0)->ios_base::sync_with_stdio(0);

    if(fopen("TASK.INP", "r")) freopen("TASK.INP", "r", stdin);
    if(fopen(TASK".INP", "r")) {
        freopen(TASK".INP", "r", stdin);
        freopen(TASK".OUT", "w", stdout);
    }

    Read();
    Solve();

    return 0;
}

Compilation message

oneway.cpp: In function 'int main()':
oneway.cpp:206:39: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  206 |     if(fopen("TASK.INP", "r")) freopen("TASK.INP", "r", stdin);
      |                                ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
oneway.cpp:208:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  208 |         freopen(TASK".INP", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
oneway.cpp:209:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  209 |         freopen(TASK".OUT", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

Subtask #1
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 13 ms 65616 KB Output is correct
2 Correct 11 ms 65780 KB Output is correct
3 Correct 11 ms 65616 KB Output is correct
4 Correct 11 ms 63568 KB Output is correct
5 Correct 11 ms 63568 KB Output is correct
6 Correct 13 ms 63568 KB Output is correct
7 Correct 11 ms 63568 KB Output is correct
8 Correct 11 ms 63660 KB Output is correct
9 Correct 11 ms 65784 KB Output is correct
10 Correct 11 ms 65616 KB Output is correct

Subtask #2
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 13 ms 65616 KB Output is correct
2 Correct 11 ms 65780 KB Output is correct
3 Correct 11 ms 65616 KB Output is correct
4 Correct 11 ms 63568 KB Output is correct
5 Correct 11 ms 63568 KB Output is correct
6 Correct 13 ms 63568 KB Output is correct
7 Correct 11 ms 63568 KB Output is correct
8 Correct 11 ms 63660 KB Output is correct
9 Correct 11 ms 65784 KB Output is correct
10 Correct 11 ms 65616 KB Output is correct
11 Correct 34 ms 69712 KB Output is correct
12 Correct 38 ms 70472 KB Output is correct
13 Correct 48 ms 73544 KB Output is correct
14 Correct 55 ms 72728 KB Output is correct
15 Correct 59 ms 75336 KB Output is correct
16 Correct 70 ms 80576 KB Output is correct
17 Correct 62 ms 80064 KB Output is correct
18 Correct 66 ms 80672 KB Output is correct
19 Correct 63 ms 83136 KB Output is correct
20 Correct 38 ms 69968 KB Output is correct
21 Correct 40 ms 69708 KB Output is correct

Subtask #3
40.0 / 40.0

# Verdict Execution time Memory Grader output
1 Correct 13 ms 65616 KB Output is correct
2 Correct 11 ms 65780 KB Output is correct
3 Correct 11 ms 65616 KB Output is correct
4 Correct 11 ms 63568 KB Output is correct
5 Correct 11 ms 63568 KB Output is correct
6 Correct 13 ms 63568 KB Output is correct
7 Correct 11 ms 63568 KB Output is correct
8 Correct 11 ms 63660 KB Output is correct
9 Correct 11 ms 65784 KB Output is correct
10 Correct 11 ms 65616 KB Output is correct
11 Correct 34 ms 69712 KB Output is correct
12 Correct 38 ms 70472 KB Output is correct
13 Correct 48 ms 73544 KB Output is correct
14 Correct 55 ms 72728 KB Output is correct
15 Correct 59 ms 75336 KB Output is correct
16 Correct 70 ms 80576 KB Output is correct
17 Correct 62 ms 80064 KB Output is correct
18 Correct 66 ms 80672 KB Output is correct
19 Correct 63 ms 83136 KB Output is correct
20 Correct 38 ms 69968 KB Output is correct
21 Correct 40 ms 69708 KB Output is correct
22 Correct 117 ms 76736 KB Output is correct
23 Correct 109 ms 77140 KB Output is correct
24 Correct 112 ms 77392 KB Output is correct
25 Correct 94 ms 83136 KB Output is correct
26 Correct 94 ms 81612 KB Output is correct
27 Correct 112 ms 80576 KB Output is correct
28 Correct 31 ms 65964 KB Output is correct
29 Correct 54 ms 69608 KB Output is correct
30 Correct 60 ms 69776 KB Output is correct
31 Correct 59 ms 70020 KB Output is correct
32 Correct 73 ms 73288 KB Output is correct