oj.uz

Submission #716228

# Submission time Handle Problem Language Result Execution time Memory
716228 2023-03-29T10:13:31 Z socpite Mousetrap (CEOI17_mousetrap) C++14
100 / 100
 1010 ms 182124 KB 
#include<bits/stdc++.h>
using namespace std;

#define f first 
#define s second

typedef long double ld;
typedef pair<int, pair<int, int>> ftype;

const int maxn = 1e6+5;
const int inf = 1e9+5;

int n, m, t;
int l, r, mid;

vector<int> g[maxn];

int dp[maxn], onp[maxn];
vector<int> path;

void onp_dfs(int x, int p){
    if(x == t){
        onp[x] = 1;
        return;
    }
    for(auto v: g[x]){
        if(v == p)continue;
        onp_dfs(v, x);
        if(onp[v]){
            dp[x]--;
            onp[x] = 1;
        }
    }
    if(onp[x] && x != t)path.push_back(x);
    //cout << x << " " << dp[x] << endl;
}

void dfs(int x, int p){
    if(x == t)return;
    vector<int> val;
    for(auto v: g[x]){
        if(v == p)continue;
        dfs(v, x);
        val.push_back(dp[v]);
    }
    if(val.empty())dp[x] = 0;
    else if(val.size() == 1)dp[x] = 1;
    else{
        sort(val.begin(), val.end());
        dp[x] = val[val.size()-2] + val.size();
    }
}

int dfs2(int x, int p, int tot = 0){
    if(x == t)return 0;
    for(auto v: g[x]){
        if(v == p)continue;
        if(onp[v])tot+=dfs2(v, x, 0);
    }
    if(onp[x])tot+=g[x].size()-(p!=0)-1;
    dp[x] += tot;   
    for(auto v: g[x]){
        if(v == p)continue;
        if(!onp[v])dfs2(v, x, tot);
    }
    //cout << x << " " << dp[x] << " " << tot << endl;
    return tot;
}

bool chk(){
    int used = 0, cap = 0;
    for(auto x: path){
        cap++;
        int last = used;
        for(auto v: g[x]){
            if(onp[v])continue;
            if(dp[v] + last > mid)used++;
        }
        //cout << used << endl;
        if(used > cap)return 0;
    }
    return used <= mid;
}


int main(){
    ios::sync_with_stdio(false);
    cin.tie(0);
    //freopen("mousetrap.inp", "r", stdin);
    // freopen("mousetrap.out", "w", stdout);
    cin >> n >> t >> m;
    for(int i = 0; i < n-1; i++){
        int a, b;
        cin >> a >> b;
        g[a].push_back(b);
        g[b].push_back(a);
    }
    onp_dfs(m, 0);
    reverse(path.begin(), path.end());
    for(auto x: path){
        for(auto v: g[x])if(!onp[v])dfs(v, x);
    }
    dfs2(m, 0);
    int l = 0, r = 2*maxn;
    while(l < r){
        mid = (l+r)>>1;
        if(chk())r = mid;
        else l = mid+1;
    }
    cout << l;
}

Subtask #1
20.0 / 20.0

# Verdict Execution time Memory Grader output
1 Correct 12 ms 23764 KB Output is correct
2 Correct 13 ms 23764 KB Output is correct
3 Correct 13 ms 23792 KB Output is correct
4 Correct 13 ms 23764 KB Output is correct
5 Correct 15 ms 23772 KB Output is correct
6 Correct 14 ms 23816 KB Output is correct
7 Correct 13 ms 23724 KB Output is correct
8 Correct 12 ms 23764 KB Output is correct
9 Correct 13 ms 23776 KB Output is correct
10 Correct 13 ms 23808 KB Output is correct

Subtask #2
25.0 / 25.0

# Verdict Execution time Memory Grader output
1 Correct 305 ms 59032 KB Output is correct
2 Correct 284 ms 55460 KB Output is correct
3 Correct 964 ms 60124 KB Output is correct
4 Correct 466 ms 41932 KB Output is correct
5 Correct 975 ms 60124 KB Output is correct
6 Correct 942 ms 60340 KB Output is correct

Subtask #3
20.0 / 20.0

# Verdict Execution time Memory Grader output
1 Correct 12 ms 23764 KB Output is correct
2 Correct 13 ms 23764 KB Output is correct
3 Correct 13 ms 23792 KB Output is correct
4 Correct 13 ms 23764 KB Output is correct
5 Correct 15 ms 23772 KB Output is correct
6 Correct 14 ms 23816 KB Output is correct
7 Correct 13 ms 23724 KB Output is correct
8 Correct 12 ms 23764 KB Output is correct
9 Correct 13 ms 23776 KB Output is correct
10 Correct 13 ms 23808 KB Output is correct
11 Correct 12 ms 23820 KB Output is correct
12 Correct 14 ms 23812 KB Output is correct
13 Correct 13 ms 23768 KB Output is correct
14 Correct 13 ms 23944 KB Output is correct
15 Correct 13 ms 23816 KB Output is correct
16 Correct 13 ms 23764 KB Output is correct
17 Correct 13 ms 23768 KB Output is correct
18 Correct 12 ms 23764 KB Output is correct
19 Correct 15 ms 23852 KB Output is correct
20 Correct 13 ms 23852 KB Output is correct
21 Correct 12 ms 23840 KB Output is correct
22 Correct 12 ms 23764 KB Output is correct

Subtask #4
35.0 / 35.0

# Verdict Execution time Memory Grader output
1 Correct 12 ms 23764 KB Output is correct
2 Correct 13 ms 23764 KB Output is correct
3 Correct 13 ms 23792 KB Output is correct
4 Correct 13 ms 23764 KB Output is correct
5 Correct 15 ms 23772 KB Output is correct
6 Correct 14 ms 23816 KB Output is correct
7 Correct 13 ms 23724 KB Output is correct
8 Correct 12 ms 23764 KB Output is correct
9 Correct 13 ms 23776 KB Output is correct
10 Correct 13 ms 23808 KB Output is correct
11 Correct 305 ms 59032 KB Output is correct
12 Correct 284 ms 55460 KB Output is correct
13 Correct 964 ms 60124 KB Output is correct
14 Correct 466 ms 41932 KB Output is correct
15 Correct 975 ms 60124 KB Output is correct
16 Correct 942 ms 60340 KB Output is correct
17 Correct 12 ms 23820 KB Output is correct
18 Correct 14 ms 23812 KB Output is correct
19 Correct 13 ms 23768 KB Output is correct
20 Correct 13 ms 23944 KB Output is correct
21 Correct 13 ms 23816 KB Output is correct
22 Correct 13 ms 23764 KB Output is correct
23 Correct 13 ms 23768 KB Output is correct
24 Correct 12 ms 23764 KB Output is correct
25 Correct 15 ms 23852 KB Output is correct
26 Correct 13 ms 23852 KB Output is correct
27 Correct 12 ms 23840 KB Output is correct
28 Correct 12 ms 23764 KB Output is correct
29 Correct 13 ms 23820 KB Output is correct
30 Correct 322 ms 72388 KB Output is correct
31 Correct 319 ms 72444 KB Output is correct
32 Correct 410 ms 158708 KB Output is correct
33 Correct 392 ms 182124 KB Output is correct
34 Correct 986 ms 73548 KB Output is correct
35 Correct 982 ms 73424 KB Output is correct
36 Correct 987 ms 82116 KB Output is correct
37 Correct 1010 ms 81940 KB Output is correct
38 Correct 732 ms 84804 KB Output is correct
39 Correct 683 ms 84780 KB Output is correct
40 Correct 735 ms 84940 KB Output is correct