oj.uz

Submission #939560

# Submission time Handle Problem Language Result Execution time Memory
939560 2024-03-06T13:59:41 Z phoenix0423 Mousetrap (CEOI17_mousetrap) C++17
100 / 100
 729 ms 162648 KB 
#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<ll, ll> pll;
#define fastio ios::sync_with_stdio(false), cin.tie(0)
#define pb push_back
#define eb emplace_back
#define f first
#define s second
#define int long long
const int maxn = 1e6 + 5;
const int INF = 1e18;
vector<int> adj[maxn];
int dp[maxn], par[maxn];
int n, t, m;

void dfs(int pos, int prev){
    if(prev != -1) adj[pos].erase(find(adj[pos].begin(), adj[pos].end(), prev));
    int mx = 0, sc = 0;
    for(auto x : adj[pos]){
        par[x] = pos;
        dfs(x, pos);    
        if(dp[x] >= mx) sc = mx, mx = dp[x];
        else sc = max(sc, dp[x]);
    }
    dp[pos] = sc + adj[pos].size();
}

signed main(void){
    fastio;
    cin>>n>>t>>m;
    t--, m--;
    for(int i = 0; i < n - 1; i++){
        int a, b;
        cin>>a>>b;
        a--, b--;
        adj[a].pb(b);
        adj[b].pb(a);
    }
    dfs(t, -1);
    int ttld = 0;
    int l = -1, r = n;
    while(l + 1 < r){
        int mid = (l + r) / 2; // cost to lead mouse into a dead end
        int ok = 1;
        int dif = 0, prev = -1;
        int canuse = 0;
        int cur = m;
        int used = 0;
        while(cur != t){
            canuse++;
            int tmp = 0;
            for(auto x : adj[cur]){
                if(x == prev) continue;
                if(dp[x] - dif + used > mid){
                    if(!canuse) ok = 0;
                    else canuse--, tmp++;
                }
            }
            used += tmp;
            dif += adj[cur].size() - (prev != -1);
            prev = cur;
            cur = par[cur];
        }
        ttld = dif;
        if(ok) r = mid;
        else l = mid;
    }
    cout<<r + ttld<<"\n";
}
/*

24 1 12
1 4
4 5
5 6
6 7
5 8
8 9
8 10
10 11
10 12
10 13
8 14
14 15
15 18
15 16
15 17
14 19
19 20
19 21
11 2
13 3
9 22
9 23
9 24
*/

Subtask #1
20.0 / 20.0

# Verdict Execution time Memory Grader output
1 Correct 6 ms 26972 KB Output is correct
2 Correct 6 ms 26972 KB Output is correct
3 Correct 7 ms 27044 KB Output is correct
4 Correct 6 ms 26972 KB Output is correct
5 Correct 6 ms 27088 KB Output is correct
6 Correct 6 ms 26972 KB Output is correct
7 Correct 6 ms 27084 KB Output is correct
8 Correct 6 ms 26976 KB Output is correct
9 Correct 6 ms 27104 KB Output is correct
10 Correct 6 ms 27100 KB Output is correct

Subtask #2
25.0 / 25.0

# Verdict Execution time Memory Grader output
1 Correct 224 ms 92020 KB Output is correct
2 Correct 196 ms 86612 KB Output is correct
3 Correct 535 ms 90208 KB Output is correct
4 Correct 230 ms 60500 KB Output is correct
5 Correct 544 ms 90212 KB Output is correct
6 Correct 565 ms 90144 KB Output is correct

Subtask #3
20.0 / 20.0

# Verdict Execution time Memory Grader output
1 Correct 6 ms 26972 KB Output is correct
2 Correct 6 ms 26972 KB Output is correct
3 Correct 7 ms 27044 KB Output is correct
4 Correct 6 ms 26972 KB Output is correct
5 Correct 6 ms 27088 KB Output is correct
6 Correct 6 ms 26972 KB Output is correct
7 Correct 6 ms 27084 KB Output is correct
8 Correct 6 ms 26976 KB Output is correct
9 Correct 6 ms 27104 KB Output is correct
10 Correct 6 ms 27100 KB Output is correct
11 Correct 6 ms 26972 KB Output is correct
12 Correct 6 ms 26972 KB Output is correct
13 Correct 6 ms 26972 KB Output is correct
14 Correct 7 ms 27228 KB Output is correct
15 Correct 6 ms 27216 KB Output is correct
16 Correct 7 ms 26972 KB Output is correct
17 Correct 6 ms 26972 KB Output is correct
18 Correct 6 ms 26972 KB Output is correct
19 Correct 7 ms 26972 KB Output is correct
20 Correct 7 ms 27100 KB Output is correct
21 Correct 7 ms 27156 KB Output is correct
22 Correct 6 ms 26972 KB Output is correct

Subtask #4
35.0 / 35.0

# Verdict Execution time Memory Grader output
1 Correct 6 ms 26972 KB Output is correct
2 Correct 6 ms 26972 KB Output is correct
3 Correct 7 ms 27044 KB Output is correct
4 Correct 6 ms 26972 KB Output is correct
5 Correct 6 ms 27088 KB Output is correct
6 Correct 6 ms 26972 KB Output is correct
7 Correct 6 ms 27084 KB Output is correct
8 Correct 6 ms 26976 KB Output is correct
9 Correct 6 ms 27104 KB Output is correct
10 Correct 6 ms 27100 KB Output is correct
11 Correct 224 ms 92020 KB Output is correct
12 Correct 196 ms 86612 KB Output is correct
13 Correct 535 ms 90208 KB Output is correct
14 Correct 230 ms 60500 KB Output is correct
15 Correct 544 ms 90212 KB Output is correct
16 Correct 565 ms 90144 KB Output is correct
17 Correct 6 ms 26972 KB Output is correct
18 Correct 6 ms 26972 KB Output is correct
19 Correct 6 ms 26972 KB Output is correct
20 Correct 7 ms 27228 KB Output is correct
21 Correct 6 ms 27216 KB Output is correct
22 Correct 7 ms 26972 KB Output is correct
23 Correct 6 ms 26972 KB Output is correct
24 Correct 6 ms 26972 KB Output is correct
25 Correct 7 ms 26972 KB Output is correct
26 Correct 7 ms 27100 KB Output is correct
27 Correct 7 ms 27156 KB Output is correct
28 Correct 6 ms 26972 KB Output is correct
29 Correct 6 ms 27104 KB Output is correct
30 Correct 213 ms 91984 KB Output is correct
31 Correct 218 ms 91992 KB Output is correct
32 Correct 332 ms 162648 KB Output is correct
33 Correct 275 ms 162468 KB Output is correct
34 Correct 537 ms 90212 KB Output is correct
35 Correct 522 ms 89972 KB Output is correct
36 Correct 697 ms 98108 KB Output is correct
37 Correct 729 ms 98008 KB Output is correct
38 Correct 485 ms 102224 KB Output is correct
39 Correct 452 ms 102252 KB Output is correct
40 Correct 464 ms 102484 KB Output is correct