Submission #642498

#	Time	Username	Problem	Language	Result	Execution time	Memory
642498		FedShat	Usmjeri (COCI17_usmjeri)	C++17	56 / 140	780 ms	262144 KiB

usmjeri

#include <bits/stdc++.h>

using namespace std;
using ll = long long;
constexpr int INF = numeric_limits<int>::max() / 2;
constexpr ll INFLL = numeric_limits<ll>::max() / 2;

template<class T>
istream &operator>>(istream &is, vector<T> &a) {
    for (auto &i : a) {
        is >> i;
    }
    return is;
}

constexpr int mod = 1e9 + 7;

struct BinaryJumps {
    static constexpr int k = 20;
    vector<vector<int>> up;
    vector<int> depth;

    BinaryJumps() {
    }

    BinaryJumps(int n) {
        up.resize(k, vector<int>(n));
        depth.resize(n);
    }

    void add_leaf(int v, int p) {
        up[0][v] = p;
        depth[v] = depth[p] + 1;
        for (int i = 1; i < k; ++i) {
            up[i][v] = up[i - 1][up[i - 1][v]];
        }
    }

    int up_k(int v, int d) {
        for (int i = k - 1; i >= 0; --i) {
            if (d >= (1 << i)) {
                v = up[i][v];
                d -= (1 << i);
            }
        }
        return v;
    }

    int LCA(int u, int v) {
        if (depth[u] < depth[v]) {
            swap(u, v);
        }
        u = up_k(u, depth[u] - depth[v]);
        for (int i = k - 1; i >= 0; --i) {
            if (up[i][u] != up[i][v]) {
                u = up[i][u];
                v = up[i][v];
            }
        }
        if (u == v) {
            return u;
        }
        return up[0][u];
    }
};

vector<vector<int>> g;
vector<int> par, sz;
BinaryJumps t;

void dfs(int v, int p) {
    par[v] = p;
    sz[v] = 1;
    for (auto u : g[v]) {
        if (u != p) {
            t.add_leaf(u, v);
            dfs(u, v);
            sz[v] += sz[u];
        }
    }
    if (p != -1) {
        g[v].erase(find(g[v].begin(), g[v].end(), p));
    }
    sort(g[v].begin(), g[v].end(), [&](int a, int b) {
        return sz[a] > sz[b];
    });
}

vector<int> tour, tin, tout, head;

void dfs_hld(int v) {
    tin[v] = tour.size();
    tour.push_back(v);
    for (auto u : g[v]) {
        if (u == g[v][0]) {
            head[u] = head[v];
        } else {
            head[u] = u;
        }
        dfs_hld(u);
    }
    tout[v] = tour.size();
}

bool is_anc(int u, int v) {
    return tin[u] <= tin[v] && tout[v] <= tout[u];
}

vector<vector<pair<int, int>>> gr;
int n;

void add_edge(int u, int v, int c) {
    gr[u].push_back({v, c});
    gr[v].push_back({u, c});
}

void build(int v, int l, int r) {
    if (l + 1 == r) {
        add_edge(v + n, l, 1);
        return;
    }
    add_edge(v + n, 2 * v + 1 + n, 1);
    add_edge(v + n, 2 * v + 2, 1);
    int m = (l + r) / 2;
    build(2 * v + 1, l, m);
    build(2 * v + 2, m, r);
}

void add_edges(int v, int l, int r, int li, int ri, int i) {
    if (li >= r || l >= ri) {
        return;
    }
    if (li <= l && r <= ri) {
        add_edge(i, v + n, 1);
        return;
    }
    int m = (l + r) / 2;
    add_edges(2 * v + 1, l, m, li, ri, i);
    add_edges(2 * v + 2, m, r, li, ri, i);
}

void add_edges_stupid(int l, int r, int v) {// [l; r)
    for (int i = l; i < r; ++i) {
        int u = tour[i];
        add_edge(u, v, 1);
    }
}

vector<int> color;
bool ok = 1;

void dfs2(int v) {
    for (auto [u, c] : gr[v]) {
        int cur = (c ? color[v] : color[v] ^ 1);
        if (color[u] == -1) {
            color[u] = cur;
            dfs2(u);
        } else {
            if (color[u] != cur) {
                ok = 0;
            }
        }
    }
}

int main() {
    cin.tie(0)->sync_with_stdio(0);
#ifdef __APPLE__
    freopen("input.txt", "r", stdin);
#endif
    int n, q;
    cin >> n >> q;
    g.resize(n);
    for (int i = 0; i < n - 1; ++i) {
        int u, v;
        cin >> u >> v;
        --u;
        --v;
        g[u].push_back(v);
        g[v].push_back(u);
    }
    t = BinaryJumps(n);
    par.resize(n);
    sz.resize(n);
    dfs(0, -1);
    gr.resize(n);
    head.resize(n);
    tin.resize(n);
    tout.resize(n);
    dfs_hld(0);
    while (q--) {
        int u, v;
        cin >> u >> v;
        --u;
        --v;
        if (t.depth[u] < t.depth[v]) {
            swap(u, v);
        }
        int l = t.LCA(u, v);
        if (l == v) {// verticals
            // int curu = u;
            // while (par[curu] != l) {
            //     add_edge(curu, par[curu], 1);// equal
            //     curu = par[curu];
            // }
            int uu = t.up_k(u, t.depth[u] - t.depth[v] - 1);
            {
                int cur = u;
                while (!is_anc(head[cur], uu)) {
                    add_edges_stupid(tin[head[cur]], tin[cur] + 1, u);
                    cur = par[head[cur]];
                }
                add_edges_stupid(tin[uu], tin[cur] + 1, u);
            }
        } else {
            // int curu = u;
            // while (par[curu] != l) {
            //     add_edge(curu, par[curu], 1);// equal
            //     curu = par[curu];
            // }
            // int curv = v;
            // while (par[curv] != l) {
            //     add_edge(curv, par[curv], 1);// equal
            //     curv = par[curv];
            // }
            // add_edge(curu, curv, 0);
            int uu = t.up_k(u, t.depth[u] - t.depth[l] - 1);
            {
                int cur = u;
                while (!is_anc(head[cur], uu)) {
                    add_edges_stupid(tin[head[cur]], tin[cur] + 1, u);
                    cur = par[head[cur]];
                }
                add_edges_stupid(tin[uu], tin[cur] + 1, u);
            }
            int vv = t.up_k(v, t.depth[v] - t.depth[l] - 1);
            {
                int cur = v;
                while (!is_anc(head[cur], vv)) {
                    add_edges_stupid(tin[head[cur]], tin[cur] + 1, v);
                    cur = par[head[cur]];
                }
                add_edges_stupid(tin[vv], tin[cur] + 1, v);
            }
            add_edge(uu, vv, 0);
        }
    }
    int ans = 1;
    color.resize(n, -1);
    for (int i = 1; i < n; ++i) {
        if (color[i] == -1) {
            color[i] = 0;
            dfs2(i);
            ans = (ans * 2ll) % mod;
        }
    }
    if (!ok) {
        cout << "0\n";
    } else {
        cout << ans << "\n";
    }
}

• Subtask 1: 0 / 14
• Subtask 2: 0 / 14
• Subtask 3: 14 / 14
• Subtask 4: 14 / 14
• Subtask 5: 14 / 14
• Subtask 6: 14 / 14
• Subtask 7: 0 / 14
• Subtask 8: 0 / 14
• Subtask 9: 0 / 14
• Subtask 10: 0 / 14