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답안 #161420

# 제출 시각 아이디 문제 언어 결과 실행 시간 메모리
161420 2019-11-02T09:50:49 Z Minnakhmetov Mousetrap (CEOI17_mousetrap) C++14
100 / 100
 1319 ms 219628 KB 
#include <bits/stdc++.h>
    
#define ll long long
#define all(aaa) aaa.begin(), aaa.end()
 
using namespace std;
 
const int N = 1e6 + 5, INF = 1e9;
vector<int> g[N];
int n, m, t;
bool term[N];

vector<vector<int>> w;

void dive(int node, int anc) {
    if (node == t)
        term[node] = 1;
    for (int to : g[node]) {
        if (to != anc) {
            dive(to, node);
            if (term[to])
                term[node] = 1;
        }
    }
}
 
int dfs(int node, int anc) {
    int adj = g[node].size() - (anc != -1);
 
    vector<int> v;
 
    for (int to : g[node]) {
        if (to != anc) {
            v.push_back(dfs(to, node) + 1);
        }
    }
 
    sort(v.rbegin(), v.rend());
 
    if (v.empty())
        return 0;
    else if (v.size() == 1)
        return 1;
    return v[1] + adj - 1;
}

int walk(int node, int anc) {
    if (node == t)
        return 0;

    vector<int> v;

    for (int to : g[node]) {
        if (to != anc && !term[to]) {
            v.push_back(dfs(to, node) + 1);                
        }
    }

    int add = 0;

    for (int to : g[node]) {
        if (to != anc) {
            if (term[to]) {
                add = walk(to, node);
            }   
        }
    }

    for (int &x : v)
        x += v.size() - 1 + add;

    sort(v.begin(), v.end());

    w.push_back(v);

    add += v.size();

    return add;
}
 
signed main() {
    ios_base::sync_with_stdio(0);
    cin.tie(NULL);
 
    cin >> n >> t >> m;
 
    m--, t--;
 
    for (int i = 0; i < n - 1; i++) {
        int a, b;
        cin >> a >> b;
        a--, b--;
        g[a].push_back(b);
        g[b].push_back(a);
    }

    dive(m, -1);
    walk(m, -1);


    reverse(all(w));

    // for (auto &v : w) {
    //     for (int x : v) {
    //         cout << x << " ";
    //     }
    //     cout << "\n";
    // }

    int l = -1, r = INF;
    while (r - l > 1) {
        int p = (l + r) >> 1;

        bool ok = true;
        int energy = 0, expended = 0;
        for (auto &v : w) {
            energy++;

            for (int x : v) {
                if (x + expended > p) {
                    if (energy == 0 || expended + 1 > p) {
                        ok = false;
                        break;
                    }
                    expended++;
                    energy--;
                }
            }
            if (!ok)
                break;
        }

        if (ok)
            r = p;
        else
            l = p;
    }

    cout << r << "\n";
 
    return 0;
}

Subtask #1
20.0 / 20.0

# 결과 실행 시간 메모리 Grader output
1 Correct 23 ms 23800 KB Output is correct
2 Correct 25 ms 23800 KB Output is correct
3 Correct 24 ms 23800 KB Output is correct
4 Correct 24 ms 23772 KB Output is correct
5 Correct 25 ms 23800 KB Output is correct
6 Correct 24 ms 23800 KB Output is correct
7 Correct 24 ms 23800 KB Output is correct
8 Correct 24 ms 23800 KB Output is correct
9 Correct 26 ms 23800 KB Output is correct
10 Correct 26 ms 23800 KB Output is correct

Subtask #2
25.0 / 25.0

# 결과 실행 시간 메모리 Grader output
1 Correct 495 ms 55288 KB Output is correct
2 Correct 471 ms 52108 KB Output is correct
3 Correct 1159 ms 56472 KB Output is correct
4 Correct 578 ms 40212 KB Output is correct
5 Correct 1167 ms 56180 KB Output is correct
6 Correct 1148 ms 56388 KB Output is correct

Subtask #3
20.0 / 20.0

# 결과 실행 시간 메모리 Grader output
1 Correct 23 ms 23800 KB Output is correct
2 Correct 25 ms 23800 KB Output is correct
3 Correct 24 ms 23800 KB Output is correct
4 Correct 24 ms 23772 KB Output is correct
5 Correct 25 ms 23800 KB Output is correct
6 Correct 24 ms 23800 KB Output is correct
7 Correct 24 ms 23800 KB Output is correct
8 Correct 24 ms 23800 KB Output is correct
9 Correct 26 ms 23800 KB Output is correct
10 Correct 26 ms 23800 KB Output is correct
11 Correct 26 ms 23800 KB Output is correct
12 Correct 24 ms 23928 KB Output is correct
13 Correct 26 ms 23904 KB Output is correct
14 Correct 28 ms 24056 KB Output is correct
15 Correct 25 ms 24056 KB Output is correct
16 Correct 25 ms 23800 KB Output is correct
17 Correct 24 ms 23928 KB Output is correct
18 Correct 43 ms 23924 KB Output is correct
19 Correct 24 ms 23800 KB Output is correct
20 Correct 23 ms 23928 KB Output is correct
21 Correct 24 ms 23928 KB Output is correct
22 Correct 54 ms 23800 KB Output is correct

Subtask #4
35.0 / 35.0

# 결과 실행 시간 메모리 Grader output
1 Correct 23 ms 23800 KB Output is correct
2 Correct 25 ms 23800 KB Output is correct
3 Correct 24 ms 23800 KB Output is correct
4 Correct 24 ms 23772 KB Output is correct
5 Correct 25 ms 23800 KB Output is correct
6 Correct 24 ms 23800 KB Output is correct
7 Correct 24 ms 23800 KB Output is correct
8 Correct 24 ms 23800 KB Output is correct
9 Correct 26 ms 23800 KB Output is correct
10 Correct 26 ms 23800 KB Output is correct
11 Correct 495 ms 55288 KB Output is correct
12 Correct 471 ms 52108 KB Output is correct
13 Correct 1159 ms 56472 KB Output is correct
14 Correct 578 ms 40212 KB Output is correct
15 Correct 1167 ms 56180 KB Output is correct
16 Correct 1148 ms 56388 KB Output is correct
17 Correct 26 ms 23800 KB Output is correct
18 Correct 24 ms 23928 KB Output is correct
19 Correct 26 ms 23904 KB Output is correct
20 Correct 28 ms 24056 KB Output is correct
21 Correct 25 ms 24056 KB Output is correct
22 Correct 25 ms 23800 KB Output is correct
23 Correct 24 ms 23928 KB Output is correct
24 Correct 43 ms 23924 KB Output is correct
25 Correct 24 ms 23800 KB Output is correct
26 Correct 23 ms 23928 KB Output is correct
27 Correct 24 ms 23928 KB Output is correct
28 Correct 54 ms 23800 KB Output is correct
29 Correct 23 ms 23804 KB Output is correct
30 Correct 501 ms 68572 KB Output is correct
31 Correct 494 ms 68732 KB Output is correct
32 Correct 656 ms 219628 KB Output is correct
33 Correct 584 ms 178296 KB Output is correct
34 Correct 1319 ms 69496 KB Output is correct
35 Correct 1274 ms 69560 KB Output is correct
36 Correct 1226 ms 88172 KB Output is correct
37 Correct 1221 ms 88304 KB Output is correct
38 Correct 986 ms 90096 KB Output is correct
39 Correct 960 ms 90092 KB Output is correct
40 Correct 1004 ms 90220 KB Output is correct