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Submission #250337

# Submission time Handle Problem Language Result Execution time Memory
250337 2020-07-17T13:15:58 Z Sorting Mousetrap (CEOI17_mousetrap) C++14
100 / 100
 1033 ms 174456 KB 
#include <iostream>
#include <cstdio>
#include <algorithm>
#include <vector>
using namespace std;
#define endl '\n'
#define ll long long
#define pi pair<int, int>
#define f first
#define s second
 
const int maxn = 1000000;
int n, m, k;
int a[maxn], d[maxn], dp[maxn];
vector<int> graph[maxn];
vector<pi> v;
 
void dfs(int c, int p){
    pi ret;
    for(int i : graph[c]){
        if(i == p) continue;
        if(p != -1) dp[i] += dp[c] + graph[c].size() - 2;
        dfs(i, c);
        a[c] |= a[i];
        ret.s = max(ret.s, dp[i]);
        if(ret.s > ret.f) swap(ret.f, ret.s);
    }
    if(graph[c].size() > 2) dp[c] = ret.s;
    dp[c] += graph[c].size() > 1;
}
 
void dfs2(int c, int p){
    if(c == m) return;
    for(int i : graph[c]){
        if(i == p) continue;
        d[i] = d[c] + 1;
        dfs2(i, c);
        if(a[c] && !a[i]) v.push_back({d[i], dp[i] + (c == k)});
    }
}
 
bool works(int x){
    int ret = 0;
    for(pi i : v){
        if(ret > i.f) return 0;
        ret += (i.s + ret) > x;
    }
    return ret <= x;
}
 
int main(){
    ios::sync_with_stdio(0);
    cin.tie(0);
    
    cin >> n >> m >> k;
    m--, k--;
    
    for(int i = 0; i < n - 1; i++){
        int u, v;
        cin >> u >> v;
        u--, v--;
        graph[u].push_back(v);
        graph[v].push_back(u);
    }
    
    a[k] = 1, d[k] = -1;
    dfs(m, -1);
    dfs2(k, -1);
    
    sort(v.begin(), v.end());
    
    int l = -1, r = n;
    while(r - l > 1){
        int mid = (l + r) / 2;
        if(works(mid)) r = mid;
        else l = mid;
    }
    
    cout << r << endl;
    
    return 0;
}

Subtask #1
20.0 / 20.0

# Verdict Execution time Memory Grader output
1 Correct 14 ms 23808 KB Output is correct
2 Correct 15 ms 23936 KB Output is correct
3 Correct 17 ms 23800 KB Output is correct
4 Correct 15 ms 23936 KB Output is correct
5 Correct 15 ms 23808 KB Output is correct
6 Correct 19 ms 23808 KB Output is correct
7 Correct 14 ms 23808 KB Output is correct
8 Correct 14 ms 23808 KB Output is correct
9 Correct 17 ms 23808 KB Output is correct
10 Correct 16 ms 23808 KB Output is correct

Subtask #2
25.0 / 25.0

# Verdict Execution time Memory Grader output
1 Correct 425 ms 78340 KB Output is correct
2 Correct 382 ms 72824 KB Output is correct
3 Correct 1033 ms 81232 KB Output is correct
4 Correct 465 ms 52472 KB Output is correct
5 Correct 993 ms 81364 KB Output is correct
6 Correct 998 ms 81252 KB Output is correct

Subtask #3
20.0 / 20.0

# Verdict Execution time Memory Grader output
1 Correct 14 ms 23808 KB Output is correct
2 Correct 15 ms 23936 KB Output is correct
3 Correct 17 ms 23800 KB Output is correct
4 Correct 15 ms 23936 KB Output is correct
5 Correct 15 ms 23808 KB Output is correct
6 Correct 19 ms 23808 KB Output is correct
7 Correct 14 ms 23808 KB Output is correct
8 Correct 14 ms 23808 KB Output is correct
9 Correct 17 ms 23808 KB Output is correct
10 Correct 16 ms 23808 KB Output is correct
11 Correct 14 ms 23808 KB Output is correct
12 Correct 14 ms 23936 KB Output is correct
13 Correct 14 ms 23936 KB Output is correct
14 Correct 15 ms 23936 KB Output is correct
15 Correct 15 ms 23936 KB Output is correct
16 Correct 14 ms 24064 KB Output is correct
17 Correct 15 ms 23936 KB Output is correct
18 Correct 15 ms 23936 KB Output is correct
19 Correct 15 ms 23936 KB Output is correct
20 Correct 15 ms 23864 KB Output is correct
21 Correct 15 ms 23936 KB Output is correct
22 Correct 14 ms 23928 KB Output is correct

Subtask #4
35.0 / 35.0

# Verdict Execution time Memory Grader output
1 Correct 14 ms 23808 KB Output is correct
2 Correct 15 ms 23936 KB Output is correct
3 Correct 17 ms 23800 KB Output is correct
4 Correct 15 ms 23936 KB Output is correct
5 Correct 15 ms 23808 KB Output is correct
6 Correct 19 ms 23808 KB Output is correct
7 Correct 14 ms 23808 KB Output is correct
8 Correct 14 ms 23808 KB Output is correct
9 Correct 17 ms 23808 KB Output is correct
10 Correct 16 ms 23808 KB Output is correct
11 Correct 425 ms 78340 KB Output is correct
12 Correct 382 ms 72824 KB Output is correct
13 Correct 1033 ms 81232 KB Output is correct
14 Correct 465 ms 52472 KB Output is correct
15 Correct 993 ms 81364 KB Output is correct
16 Correct 998 ms 81252 KB Output is correct
17 Correct 14 ms 23808 KB Output is correct
18 Correct 14 ms 23936 KB Output is correct
19 Correct 14 ms 23936 KB Output is correct
20 Correct 15 ms 23936 KB Output is correct
21 Correct 15 ms 23936 KB Output is correct
22 Correct 14 ms 24064 KB Output is correct
23 Correct 15 ms 23936 KB Output is correct
24 Correct 15 ms 23936 KB Output is correct
25 Correct 15 ms 23936 KB Output is correct
26 Correct 15 ms 23864 KB Output is correct
27 Correct 15 ms 23936 KB Output is correct
28 Correct 14 ms 23928 KB Output is correct
29 Correct 14 ms 23808 KB Output is correct
30 Correct 402 ms 78328 KB Output is correct
31 Correct 400 ms 78332 KB Output is correct
32 Correct 493 ms 174364 KB Output is correct
33 Correct 515 ms 174456 KB Output is correct
34 Correct 997 ms 81208 KB Output is correct
35 Correct 988 ms 81240 KB Output is correct
36 Correct 999 ms 93036 KB Output is correct
37 Correct 989 ms 92984 KB Output is correct
38 Correct 769 ms 91500 KB Output is correct
39 Correct 805 ms 91380 KB Output is correct
40 Correct 829 ms 91500 KB Output is correct