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Submission #389240

# Submission time Handle Problem Language Result Execution time Memory
389240 2021-04-14T01:34:41 Z syl123456 Easter Eggs (info1cup17_eastereggs) C++17
100 / 100
 17 ms 584 KB 
#include <bits/stdc++.h>
#include "grader.h"

using namespace std;
vector<vector<int>> g, pa;
vector<int> dep, ord;
void dfs(int i, int p) {
    pa[i][0] = p;
    ord.push_back(i);
    dep[i] = dep[p] + 1;
    for (int j : g[i]) if (j != p)
        dfs(j, i);
}
int lca(int i, int j) {
    if (dep[i] < dep[j]) swap(i, j);
    for (int ii = 9; ~ii; --ii) if (dep[pa[i][ii]] >= dep[j])
        i = pa[i][ii];
    for (int ii = 9; ~ii; --ii) if (pa[i][ii] != pa[j][ii])
        i = pa[i][ii], j = pa[j][ii];
    return i == j ? i : pa[i][0];
}
int findEgg (int N, vector < pair < int, int > > bridges)
{
    g.assign(N, vector<int>()), pa.assign(N, vector<int>(10));
    dep.resize(N), dep[0] = -1;
    for (auto i : bridges) {
        int x = i.first - 1, y = i.second - 1;
        g[x].push_back(y), g[y].push_back(x);
    }
    dfs(0, 0);
    for (int i = 1; i < 10; ++i) for (int j = 0; j < N; ++j)
        pa[j][i] = pa[pa[j][i - 1]][i - 1];
    int l = 0, r = N;
    while (l < r - 1) {
        int m = l + r >> 1, x = ord[l];
        for (int i = l + 1; i < m; ++i)
            x = lca(x, ord[i]);
        vector<bool> vis(N, false);
        vector<int> ans(1, x + 1);
        vis[x] = true;
        for (int i = l; i < m; ++i) for (int j = ord[i]; !vis[j]; j = pa[j][0])
            vis[j] = true, ans.push_back(j + 1);
        if (query(ans)) r = m;
        else l = m;
    }
    return ord[l] + 1;
}

Compilation message

eastereggs.cpp: In function 'int findEgg(int, std::vector<std::pair<int, int> >)':
eastereggs.cpp:35:19: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   35 |         int m = l + r >> 1, x = ord[l];
      |                 ~~^~~

Subtask #1
40.0 / 40.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 200 KB Number of queries: 4
2 Correct 1 ms 200 KB Number of queries: 4
3 Correct 1 ms 200 KB Number of queries: 4
4 Correct 1 ms 204 KB Number of queries: 4

Subtask #2
40.0 / 40.0

# Verdict Execution time Memory Grader output
1 Correct 4 ms 400 KB Number of queries: 8
2 Correct 10 ms 472 KB Number of queries: 9
3 Correct 14 ms 464 KB Number of queries: 9
4 Correct 14 ms 576 KB Number of queries: 9

Subtask #3
20.0 / 20.0

# Verdict Execution time Memory Grader output
1 Correct 17 ms 500 KB Number of queries: 9
2 Correct 13 ms 584 KB Number of queries: 9
3 Correct 14 ms 568 KB Number of queries: 9
4 Correct 14 ms 584 KB Number of queries: 9