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Submission #577598

# Submission time Handle Problem Language Result Execution time Memory
577598 2022-06-15T06:20:27 Z saarang123 Usmjeri (COCI17_usmjeri) C++17
140 / 140
 445 ms 87052 KB 
#include <bits/stdc++.h>
using namespace std;

using ll = long long;

const int MXN = 300 * 1000 + 3;
const int LGN = 19, mod = 1e9 + 7;
vector<int> g[MXN];
vector<array<int, 2>> adj[MXN];
int dt[MXN], cmin[MXN], sub[MXN], up[MXN][LGN], col[MXN];
int n, m;

void init(int v = 1, int p = 0) {
    for(int i = 1; i < LGN; i++)
        up[v][i] = up[up[v][i - 1]][i - 1];

    for(int u : g[v]) if(u != p) {
        up[u][0] = v;
        dt[u] = dt[v] + 1;
        cmin[u] = dt[u];
        init(u, v);
    }
}

int kth(int v, int k) {
    for(int i = 0; i < LGN; i++)
        if(k >> i & 1)
            v = up[v][i];
    return v;
}

int LCA(int u, int v) {
    if(dt[u] > dt[v])
        swap(u, v);
    v = kth(v, dt[v] - dt[u]);
    if(u == v)
        return v;
    for(int i = LGN - 1; i >= 0; i--)
        if(up[u][i] != up[v][i])
            u = up[u][i], v = up[v][i];
    return up[u][0];
}

int connect(int v = 1, int p = 1) {
    sub[v] = cmin[v];
    for(int u : g[v]) if(u != p) {
        sub[v] = min(sub[v], connect(u, v));
        if(sub[u] < dt[v]) {
            adj[u].push_back({v, 0});
            adj[v].push_back({u, 0});
        }
    }
    return sub[v];
}

bool dfs(int v, int c) {
    col[v] = c;
    for(auto &[u, i] : adj[v]) {
        if(col[u] != -1 && col[u] != (c ^ i))
            return false;
        else if(col[u] == -1)
            if(!dfs(u, c ^ i))
                return false;
    }
    return true;
}

ll fexpo(ll a, int b) {
    ll res = 1;
    while(b) {
        if(b & 1)
            (res *= a) %= mod;
        (a *= a) %= mod;
        b >>= 1;
    }
    return res;
}

int main() {
    std::ios::sync_with_stdio(0);
    std::cin.tie(0);
    cin >> n >> m;
    memset(col, -1, sizeof col);
    for(int u, v, i = 1; i < n; i++) {
        cin >> u >> v;
        g[u].push_back(v);
        g[v].push_back(u);
    }
    init();
    for(int u, v, i = 0; i < m; i++) {
        cin >> u >> v; 
        int lc = LCA(u, v);
        //cout << u << ' ' << v << ": " << lc << endl;
        for(int x : {u, v})
            cmin[x] = min(cmin[x], dt[lc]);
        if(u != lc && v != lc) {
            adj[u].push_back({v, 1});
            adj[v].push_back({u, 1});
        }
    }
    connect();
    int cnt = 0;
    for(int i = 2; i <= n; i++) if(col[i] < 0) {
        if(!dfs(i, 0))
            return cout << 0 << '\n', 0;
        cnt++;
    }
    cout << fexpo(2LL, cnt) << '\n';
    return 0;
}

Subtask #1
14.0 / 14.0

# Verdict Execution time Memory Grader output
1 Correct 104 ms 40940 KB Output is correct

Subtask #2
14.0 / 14.0

# Verdict Execution time Memory Grader output
1 Correct 217 ms 87052 KB Output is correct

Subtask #3
14.0 / 14.0

# Verdict Execution time Memory Grader output
1 Correct 10 ms 15700 KB Output is correct
2 Correct 11 ms 15956 KB Output is correct

Subtask #4
14.0 / 14.0

# Verdict Execution time Memory Grader output
1 Correct 10 ms 15704 KB Output is correct
2 Correct 10 ms 15836 KB Output is correct

Subtask #5
14.0 / 14.0

# Verdict Execution time Memory Grader output
1 Correct 14 ms 16400 KB Output is correct
2 Correct 11 ms 16212 KB Output is correct

Subtask #6
14.0 / 14.0

# Verdict Execution time Memory Grader output
1 Correct 13 ms 16340 KB Output is correct
2 Correct 11 ms 16212 KB Output is correct

Subtask #7
14.0 / 14.0

# Verdict Execution time Memory Grader output
1 Correct 383 ms 62084 KB Output is correct
2 Correct 400 ms 63964 KB Output is correct
3 Correct 237 ms 46724 KB Output is correct

Subtask #8
14.0 / 14.0

# Verdict Execution time Memory Grader output
1 Correct 445 ms 66080 KB Output is correct
2 Correct 440 ms 66108 KB Output is correct
3 Correct 264 ms 50444 KB Output is correct

Subtask #9
14.0 / 14.0

# Verdict Execution time Memory Grader output
1 Correct 391 ms 66764 KB Output is correct
2 Correct 378 ms 63052 KB Output is correct
3 Correct 338 ms 50492 KB Output is correct

Subtask #10
14.0 / 14.0

# Verdict Execution time Memory Grader output
1 Correct 425 ms 67272 KB Output is correct
2 Correct 415 ms 67704 KB Output is correct
3 Correct 276 ms 47172 KB Output is correct