Submission #441749

#	Time	Username	Problem	Language	Result	Execution time	Memory
441749		training4usaco	Burza (COCI16_burza)	C++11	0 / 160	10 ms	9164 KiB

burza

#include <iostream>
#include <vector>
using namespace std;

int n, k;
vector<vector<int>> adj;
vector<vector<int>> newadj;  // ignore nodes deeper than k
vector<int> depth;
vector<vector<int>> parents;
int timer = 0;
vector<int> sttime;
vector<int> fntime;
vector<int> loc;
vector<int> dp (1 << 21);

bool depthCheck(int v, int p) {
    if(depth[v] == k) {
        return true;
    }

    bool ret = false;
    for(auto next : adj[v]) {
        if(next == p) {
            continue;
        }
        depth[next] = depth[v] + 1;
        bool option = depthCheck(next, v);
        ret |= option;

        if(option) {
            newadj[v].push_back(next);
        }
    }
    return ret;
}

void dfs(int v, int p) {
    parents[v][0] = v;
    parents[v][1] = p;

    if(p != -1) {
        for(int i = 2; i <= depth[v] + 1; ++i) {
        // parent of parents[v][i - 1] = parents[v][i]
        parents[v][i] = parents[parents[v][i - 1]][1];
        }
    }

    ++timer;
    cout << "v, p, timer: " << v << ", " << p << ", " << timer << endl;
    sttime[v] = timer;
    loc[timer] = v;

    for(int next : newadj[v]) {
        if(next != p) {
            dfs(next, v);
        }
    }
    fntime[v] = timer;
}

int main() {
    cin >> n >> k;
    if(k > 20) {
        cout << "DA" << endl;
        return 0;
    }

    adj = vector<vector<int>>(n + 1);
    newadj = vector<vector<int>>(n + 1);
    depth = vector<int>(n + 1, 0);
    parents = vector<vector<int>>(n + 1, vector<int>(n + 1, -1));
    sttime = vector<int>(n + 1);
    fntime = vector<int>(n + 1);
    loc = vector<int>(n + 1);

    for(int i = 0; i < n - 1; ++i) {
        int a, b;
        cin >> a >> b;

        adj[a].push_back(b);
        adj[b].push_back(a);
    }

    if(!depthCheck(1, -1)) {  // graph is too shallow
        cout << "DA" << endl;
        return 0;
    }

    dfs(1, -1);

    // cout << endl;
    // for (int i = 1; i <= n; i++) {
	// 	cout << i << ": " << sttime[i] << " " << fntime[i] << endl;
    // }

    for(int mask = 0; mask < (1 << k); ++mask) {
        int res = dp[mask];
        while(res <= timer && depth[loc[res]] < k) {
            ++res;
        }

        if(res > timer) {
            cout << "DA" << endl;
            return 0;
        }
        int v = loc[res];

        for(int i = 0; i < k; ++i) {
            if(mask && (1 << i)) {
                continue;
            }
            int p = parents[v][k - (i + 1)];
            dp[mask | (1 << i)] = max(dp[mask | (1 << i)], fntime[p] + 1);
        }
    }
    cout << "NE" << endl;
}

Compilation message (stderr)

burza.cpp: In function 'int main()':
burza.cpp:109:27: warning: '<<' in boolean context, did you mean '<'? [-Wint-in-bool-context]
  109 |             if(mask && (1 << i)) {
      |                        ~~~^~~~~

• Subtask 1: 0 / 16
• Subtask 2: 0 / 16
• Subtask 3: 0 / 16
• Subtask 4: 0 / 16
• Subtask 5: 0 / 16
• Subtask 6: 0 / 16
• Subtask 7: 0 / 16
• Subtask 8: 0 / 16
• Subtask 9: 0 / 16
• Subtask 10: 0 / 16