oj.uz

Submission #593869

# Submission time Handle Problem Language Result Execution time Memory
593869 2022-07-11T17:03:18 Z alextodoran Mousetrap (CEOI17_mousetrap) C++17
100 / 100
 699 ms 178320 KB 
/**
 ____ ____ ____ ____ ____
||a |||t |||o |||d |||o ||
||__|||__|||__|||__|||__||
|/__\|/__\|/__\|/__\|/__\|

**/

#include <bits/stdc++.h>

using namespace std;

typedef long long ll;

const int N_MAX = (int) 1e6;

int N, T, M;
vector <int> adj[N_MAX + 2];

int parent[N_MAX + 2];
int up[N_MAX + 2];
int down[N_MAX + 2];

void dfs (int u) {
    int sons = (int) adj[u].size() - (u != T);
    int max1 = 0, max2 = 0;
    for (int v : adj[u]) {
        if (v != parent[u]) {
            parent[v] = u;
            up[v] = up[u] + (u == T ? 1 : sons);
            dfs(v);
            if (down[v] >= max1) {
                max2 = max1;
                max1 = down[v];
            } else if (down[v] > max2) {
                max2 = down[v];
            }
        }
    }
    if (sons == 0) {
        down[u] = up[u];
    } else if (sons == 1) {
        down[u] = up[u] + 1;
    } else {
        down[u] = max2;
    }
}

int path[N_MAX + 2];
int len;

bool check (int answer) {
    int block = 0;
    for (int i = 1; i <= len; i++) {
        int here = 0;
        int u = path[i];
        for (int v : adj[u]) {
            if (v != parent[u] && v != path[i - 1]) {
                if (block + down[v] > answer) {
                    here++;
                }
            }
        }
        block += here;
        if (block > i) {
            return false;
        }
    }
    return (block <= answer);
}

int main () {
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);

    cin >> N >> T >> M;
    for (int i = 1; i <= N - 1; i++) {
        int u, v;
        cin >> u >> v;
        adj[u].push_back(v);
        adj[v].push_back(u);
    }

    dfs(T);

    int u = M;
    while (u != T) {
        path[++len] = u;
        u = parent[u];
    }
    path[++len] = T;

    for (int i = 1; i <= len; i++) {
        int u = path[i];
        for (int v : adj[u]) {
            if (v != parent[u] && v != path[i - 1]) {
                down[v] -= (len - i) + (i > 1);
            }
        }
    }

    int l = 0, r = N;
    while (l < r) {
        int mid = (l + r) / 2;
        if (check(mid) == true) {
            r = mid;
        } else {
            l = mid + 1;
        }
    }
    cout << l << "\n";

    return 0;
}

Subtask #1
20.0 / 20.0

# Verdict Execution time Memory Grader output
1 Correct 14 ms 23764 KB Output is correct
2 Correct 12 ms 23764 KB Output is correct
3 Correct 14 ms 23816 KB Output is correct
4 Correct 12 ms 23764 KB Output is correct
5 Correct 12 ms 23840 KB Output is correct
6 Correct 14 ms 23764 KB Output is correct
7 Correct 13 ms 23764 KB Output is correct
8 Correct 12 ms 23768 KB Output is correct
9 Correct 12 ms 23764 KB Output is correct
10 Correct 13 ms 23820 KB Output is correct

Subtask #2
25.0 / 25.0

# Verdict Execution time Memory Grader output
1 Correct 261 ms 66832 KB Output is correct
2 Correct 240 ms 62544 KB Output is correct
3 Correct 632 ms 67948 KB Output is correct
4 Correct 301 ms 45820 KB Output is correct
5 Correct 654 ms 67984 KB Output is correct
6 Correct 632 ms 67944 KB Output is correct

Subtask #3
20.0 / 20.0

# Verdict Execution time Memory Grader output
1 Correct 14 ms 23764 KB Output is correct
2 Correct 12 ms 23764 KB Output is correct
3 Correct 14 ms 23816 KB Output is correct
4 Correct 12 ms 23764 KB Output is correct
5 Correct 12 ms 23840 KB Output is correct
6 Correct 14 ms 23764 KB Output is correct
7 Correct 13 ms 23764 KB Output is correct
8 Correct 12 ms 23768 KB Output is correct
9 Correct 12 ms 23764 KB Output is correct
10 Correct 13 ms 23820 KB Output is correct
11 Correct 13 ms 23816 KB Output is correct
12 Correct 13 ms 23820 KB Output is correct
13 Correct 13 ms 23772 KB Output is correct
14 Correct 12 ms 23892 KB Output is correct
15 Correct 12 ms 23900 KB Output is correct
16 Correct 13 ms 23888 KB Output is correct
17 Correct 14 ms 23828 KB Output is correct
18 Correct 13 ms 23776 KB Output is correct
19 Correct 12 ms 23892 KB Output is correct
20 Correct 12 ms 23892 KB Output is correct
21 Correct 13 ms 23888 KB Output is correct
22 Correct 13 ms 23796 KB Output is correct

Subtask #4
35.0 / 35.0

# Verdict Execution time Memory Grader output
1 Correct 14 ms 23764 KB Output is correct
2 Correct 12 ms 23764 KB Output is correct
3 Correct 14 ms 23816 KB Output is correct
4 Correct 12 ms 23764 KB Output is correct
5 Correct 12 ms 23840 KB Output is correct
6 Correct 14 ms 23764 KB Output is correct
7 Correct 13 ms 23764 KB Output is correct
8 Correct 12 ms 23768 KB Output is correct
9 Correct 12 ms 23764 KB Output is correct
10 Correct 13 ms 23820 KB Output is correct
11 Correct 261 ms 66832 KB Output is correct
12 Correct 240 ms 62544 KB Output is correct
13 Correct 632 ms 67948 KB Output is correct
14 Correct 301 ms 45820 KB Output is correct
15 Correct 654 ms 67984 KB Output is correct
16 Correct 632 ms 67944 KB Output is correct
17 Correct 13 ms 23816 KB Output is correct
18 Correct 13 ms 23820 KB Output is correct
19 Correct 13 ms 23772 KB Output is correct
20 Correct 12 ms 23892 KB Output is correct
21 Correct 12 ms 23900 KB Output is correct
22 Correct 13 ms 23888 KB Output is correct
23 Correct 14 ms 23828 KB Output is correct
24 Correct 13 ms 23776 KB Output is correct
25 Correct 12 ms 23892 KB Output is correct
26 Correct 12 ms 23892 KB Output is correct
27 Correct 13 ms 23888 KB Output is correct
28 Correct 13 ms 23796 KB Output is correct
29 Correct 13 ms 23724 KB Output is correct
30 Correct 273 ms 80196 KB Output is correct
31 Correct 277 ms 80184 KB Output is correct
32 Correct 394 ms 178320 KB Output is correct
33 Correct 307 ms 174216 KB Output is correct
34 Correct 657 ms 81184 KB Output is correct
35 Correct 665 ms 81324 KB Output is correct
36 Correct 697 ms 90956 KB Output is correct
37 Correct 699 ms 90788 KB Output is correct
38 Correct 488 ms 93644 KB Output is correct
39 Correct 512 ms 93816 KB Output is correct
40 Correct 488 ms 93620 KB Output is correct