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Submission #950612

# Submission time Handle Problem Language Result Execution time Memory
950612 2024-03-20T13:41:40 Z 12345678 Usmjeri (COCI17_usmjeri) C++17
140 / 140
 393 ms 118768 KB 
#include <bits/stdc++.h>

using namespace std;

const int nx=3e5+5, kx=19, mod=1e9+7;

long long n, m, u, v, lvl[nx], pa[nx][kx], a, b, dp[nx], vs[nx], c[nx], cnt, f, res=1;
vector<int> d[nx];
vector<pair<int, int>> t[nx];

void dfs(int u, int p)
{
    lvl[u]=lvl[p]+1;
    pa[u][0]=p;
    for (int i=1; i<kx; i++) pa[u][i]=pa[pa[u][i-1]][i-1];
    for (auto v:d[u]) if (v!=p) dfs(v, u);
}

int lca(int u, int v)
{
    if (lvl[u]>lvl[v]) swap(u, v);
    for (int i=kx-1; i>=0; i--) if (lvl[pa[v][i]]>=lvl[u]) v=pa[v][i];
    if (u==v) return u;
    for (int i=kx-1; i>=0; i--) if (pa[u][i]!=pa[v][i]) u=pa[u][i], v=pa[v][i];
    return pa[u][0];
}

void dfs2(int u, int p)
{
    for (auto v:d[u]) 
    {
        if (v==p) continue;
        dfs2(v, u);
        dp[u]=min(dp[u], dp[v]);
        if (dp[v]<lvl[u]) t[u].push_back({v, 0}), t[v].push_back({u, 0});
    }
}

void dfs3(int u)
{
    if (f) return;
    vs[u]=1;
    for (auto [v, s]:t[u])
    {
        if (!vs[v]) c[v]=(s==0)?c[u]:(1-c[u]), dfs3(v);
        else if ((s==0&&c[v]!=c[u])||(s==1&&c[v]==c[u])) f=1;
    }
}

int main()
{
    cin.tie(NULL)->sync_with_stdio(false);
    cin>>n>>m;
    for (int i=1; i<n; i++) cin>>u>>v, d[u].push_back(v), d[v].push_back(u);
    dfs(1, 1);
    for (int i=1; i<=n; i++) dp[i]=INT_MAX;
    for (int i=1; i<=m; i++) 
    {
        cin>>a>>b;
        int l=lca(a, b);
        dp[a]=min(dp[a], lvl[l]);
        dp[b]=min(dp[b], lvl[l]);
        if (l!=a&&l!=b) t[a].push_back({b, 1}), t[b].push_back({a, 1});
    }
    for (int i=1; i<=n; i++) c[i]=-1;
    dfs2(1, 1);
    for (int i=2; i<=n; i++)
    {
        if (vs[i]) continue;
        res=(res*2)%mod;
        c[i]=0;
        dfs3(i);
        if (f) return cout<<0, 0;
    }
    cout<<res;
}

Subtask #1
14.0 / 14.0

# Verdict Execution time Memory Grader output
1 Correct 111 ms 56592 KB Output is correct

Subtask #2
14.0 / 14.0

# Verdict Execution time Memory Grader output
1 Correct 223 ms 118768 KB Output is correct

Subtask #3
14.0 / 14.0

# Verdict Execution time Memory Grader output
1 Correct 4 ms 19036 KB Output is correct
2 Correct 7 ms 19112 KB Output is correct

Subtask #4
14.0 / 14.0

# Verdict Execution time Memory Grader output
1 Correct 5 ms 19036 KB Output is correct
2 Correct 6 ms 19036 KB Output is correct

Subtask #5
14.0 / 14.0

# Verdict Execution time Memory Grader output
1 Correct 9 ms 19548 KB Output is correct
2 Correct 7 ms 19292 KB Output is correct

Subtask #6
14.0 / 14.0

# Verdict Execution time Memory Grader output
1 Correct 8 ms 19548 KB Output is correct
2 Correct 6 ms 19216 KB Output is correct

Subtask #7
14.0 / 14.0

# Verdict Execution time Memory Grader output
1 Correct 364 ms 89380 KB Output is correct
2 Correct 360 ms 91092 KB Output is correct
3 Correct 221 ms 67124 KB Output is correct

Subtask #8
14.0 / 14.0

# Verdict Execution time Memory Grader output
1 Correct 393 ms 93336 KB Output is correct
2 Correct 352 ms 93188 KB Output is correct
3 Correct 257 ms 70696 KB Output is correct

Subtask #9
14.0 / 14.0

# Verdict Execution time Memory Grader output
1 Correct 347 ms 94104 KB Output is correct
2 Correct 336 ms 90136 KB Output is correct
3 Correct 237 ms 70968 KB Output is correct

Subtask #10
14.0 / 14.0

# Verdict Execution time Memory Grader output
1 Correct 380 ms 94608 KB Output is correct
2 Correct 346 ms 95060 KB Output is correct
3 Correct 213 ms 67668 KB Output is correct