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Submission #563728

# Submission time Handle Problem Language Result Execution time Memory
563728 2022-05-18T04:10:21 Z hoanghq2004 Mousetrap (CEOI17_mousetrap) C++14
100 / 100
 1020 ms 195936 KB 
#include <bits/stdc++.h>

using namespace std;

const int N = 1e6 + 10;

int n, S, T;
vector <int> g[N];
int f[N], flag[N];

int cnt;

void dfs(int u, int p) {
    int best[3] = {0, 0, 0};
    for (auto v: g[u]) {
        if (v == p) continue;
        dfs(v, u);
        best[2] = f[v];
        sort(best, best + 3);
        reverse(best, best + 3);
    }
    f[u] = best[1] + g[u].size() - 1;
}

int par[N];

void init(int u, int p) {
    par[u] = p;
    for (auto v: g[u]) {
        if (v == p) continue;
        init(v, u);
    }
}

vector <int> s[N];

int main() {
    ios :: sync_with_stdio(0); cin.tie(0);
    cin >> n >> T >> S;
    for (int i = 1; i < n; ++i) {
        int u, v;
        cin >> u >> v;
        g[u].push_back(v);
        g[v].push_back(u);
    }
    init(S, 0);
    vector <int> path;
    for (int u = T; u != S; u = par[u]) flag[par[u]] = 1, path.push_back(par[u]);
    int need = 0;
    for (auto u: path) {
        for (auto v: g[u]) {
            if (flag[v]) continue;
            if (v == T) continue;
            dfs(v, u);
            s[u].push_back(f[v]);
        }
        sort(s[u].begin(), s[u].end());
        for (auto& x: s[u]) x += ++need;
        reverse(s[u].begin(), s[u].end());
    }
    reverse(path.begin(), path.end());
    auto check = [&](int limit) {
        int k = 0, tot = 0;
        for (auto u: path) {
            ++k;
            int i = 0;
            while (i < s[u].size() && s[u][i] + tot > limit) {
                --k;
                if (k < 0) return 0;
                ++tot;
                ++i;
            }
        }
        if (tot > limit) return 0;
        return 1;
    };
    int L = 0, R = n;
    while (L < R) {
        int mid = L + R >> 1;
        if (check(mid)) R = mid;
        else L = mid + 1;
    }
    cout << L;
}

Compilation message

mousetrap.cpp: In lambda function:
mousetrap.cpp:67:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   67 |             while (i < s[u].size() && s[u][i] + tot > limit) {
      |                    ~~^~~~~~~~~~~~~
mousetrap.cpp: In function 'int main()':
mousetrap.cpp:79:21: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   79 |         int mid = L + R >> 1;
      |                   ~~^~~

Subtask #1
20.0 / 20.0

# Verdict Execution time Memory Grader output
1 Correct 26 ms 47176 KB Output is correct
2 Correct 26 ms 47236 KB Output is correct
3 Correct 25 ms 47188 KB Output is correct
4 Correct 25 ms 47292 KB Output is correct
5 Correct 29 ms 47172 KB Output is correct
6 Correct 26 ms 47264 KB Output is correct
7 Correct 26 ms 47180 KB Output is correct
8 Correct 30 ms 47284 KB Output is correct
9 Correct 29 ms 47188 KB Output is correct
10 Correct 26 ms 47180 KB Output is correct

Subtask #2
25.0 / 25.0

# Verdict Execution time Memory Grader output
1 Correct 309 ms 86412 KB Output is correct
2 Correct 280 ms 82508 KB Output is correct
3 Correct 853 ms 87400 KB Output is correct
4 Correct 392 ms 67420 KB Output is correct
5 Correct 851 ms 87568 KB Output is correct
6 Correct 864 ms 87516 KB Output is correct

Subtask #3
20.0 / 20.0

# Verdict Execution time Memory Grader output
1 Correct 26 ms 47176 KB Output is correct
2 Correct 26 ms 47236 KB Output is correct
3 Correct 25 ms 47188 KB Output is correct
4 Correct 25 ms 47292 KB Output is correct
5 Correct 29 ms 47172 KB Output is correct
6 Correct 26 ms 47264 KB Output is correct
7 Correct 26 ms 47180 KB Output is correct
8 Correct 30 ms 47284 KB Output is correct
9 Correct 29 ms 47188 KB Output is correct
10 Correct 26 ms 47180 KB Output is correct
11 Correct 27 ms 47200 KB Output is correct
12 Correct 32 ms 47292 KB Output is correct
13 Correct 34 ms 47316 KB Output is correct
14 Correct 27 ms 47336 KB Output is correct
15 Correct 26 ms 47316 KB Output is correct
16 Correct 27 ms 47216 KB Output is correct
17 Correct 29 ms 47316 KB Output is correct
18 Correct 27 ms 47300 KB Output is correct
19 Correct 28 ms 47208 KB Output is correct
20 Correct 26 ms 47260 KB Output is correct
21 Correct 28 ms 47352 KB Output is correct
22 Correct 27 ms 47344 KB Output is correct

Subtask #4
35.0 / 35.0

# Verdict Execution time Memory Grader output
1 Correct 26 ms 47176 KB Output is correct
2 Correct 26 ms 47236 KB Output is correct
3 Correct 25 ms 47188 KB Output is correct
4 Correct 25 ms 47292 KB Output is correct
5 Correct 29 ms 47172 KB Output is correct
6 Correct 26 ms 47264 KB Output is correct
7 Correct 26 ms 47180 KB Output is correct
8 Correct 30 ms 47284 KB Output is correct
9 Correct 29 ms 47188 KB Output is correct
10 Correct 26 ms 47180 KB Output is correct
11 Correct 309 ms 86412 KB Output is correct
12 Correct 280 ms 82508 KB Output is correct
13 Correct 853 ms 87400 KB Output is correct
14 Correct 392 ms 67420 KB Output is correct
15 Correct 851 ms 87568 KB Output is correct
16 Correct 864 ms 87516 KB Output is correct
17 Correct 27 ms 47200 KB Output is correct
18 Correct 32 ms 47292 KB Output is correct
19 Correct 34 ms 47316 KB Output is correct
20 Correct 27 ms 47336 KB Output is correct
21 Correct 26 ms 47316 KB Output is correct
22 Correct 27 ms 47216 KB Output is correct
23 Correct 29 ms 47316 KB Output is correct
24 Correct 27 ms 47300 KB Output is correct
25 Correct 28 ms 47208 KB Output is correct
26 Correct 26 ms 47260 KB Output is correct
27 Correct 28 ms 47352 KB Output is correct
28 Correct 27 ms 47344 KB Output is correct
29 Correct 32 ms 47188 KB Output is correct
30 Correct 343 ms 86492 KB Output is correct
31 Correct 329 ms 86352 KB Output is correct
32 Correct 364 ms 114904 KB Output is correct
33 Correct 380 ms 195936 KB Output is correct
34 Correct 953 ms 87648 KB Output is correct
35 Correct 1020 ms 87576 KB Output is correct
36 Correct 918 ms 93116 KB Output is correct
37 Correct 930 ms 93172 KB Output is correct
38 Correct 712 ms 94892 KB Output is correct
39 Correct 706 ms 94888 KB Output is correct
40 Correct 695 ms 94816 KB Output is correct