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Submission #616917

# Submission time Handle Problem Language Result Execution time Memory
616917 2022-08-01T07:40:30 Z nghiass001 Mousetrap (CEOI17_mousetrap) C++17
100 / 100
 1114 ms 217292 KB 
#include <bits/stdc++.h>
#define FOR(i, l, r) for(int i=(l); i<=(r); ++i)
#define REP(i, l, r) for(int i=(l); i<(r); ++i)
#define FORD(i, r, l) for(int i=(r); i>=(l); --i)
#define REPD(i, r, l)  for(int i=(r)-1; i>=(l); --i)
using namespace std;
const int N = 1e6 + 5;
int n, trap, mouse, cstep[N], deg[N], sdeg[N], p[N], avail[N];
vector<int> S[N], Q[N];
 
void Enter() {
    cin >> n >> trap >> mouse;
    REP(i, 1, n) {
        int u, v;
        cin >> u >> v;
        S[u].push_back(v);
        S[v].push_back(u);
    }
}
 
void DFS(int u, int pa) {
    if (u == mouse) avail[u] = 1;
    p[u] = pa;
    for(int v : S[u]) if (v != pa) {
        DFS(v, u);
        if (avail[v]) avail[u] = 1;
        else {
            Q[u].push_back(v);
            ++deg[u];
        }
    }
    sort(Q[u].begin(), Q[u].end(), [] (int x, int y) { return cstep[x] > cstep[y]; });
    if (deg[u] <= 1) cstep[u] = deg[u];
    if (deg[u] > 1) cstep[u] = cstep[Q[u][1]] + deg[u];
}
 
void DFS2(int u) {
    cstep[u] += sdeg[u];
    for(int v : S[u]) if (v != p[u]) {
        sdeg[v] = deg[u] + sdeg[u];
        DFS2(v);
    }
}
 
bool check(int x) {
    int sl = 0, timer = 0;
    for(int i = mouse; i != trap; i = p[i]) {
        ++timer;
        int c_now = 0;
        for(int v : Q[i]) if (cstep[v] + sl - c_now > x) ++sl, ++c_now;
        if (sl > timer || sl > x) return false;
    }
    return true;
}
 
void Process() {
    DFS(trap, 0);
    deg[trap] = 0;
    DFS2(trap);
    int l = 0, r = n, mid;
    while (l < r) {
        mid = (l + r) / 2;
        if (check(mid)) r = mid;
        else l = mid + 1;
    }
    cout << l;
}
 
int main()
{
    #define file "mousetrap"
    if (fopen(file".inp", "r")) {
        freopen(file".inp", "r", stdin);
        freopen(file".out", "w", stdout);
    }
    ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL);
    Enter();
    Process();
}

Compilation message

mousetrap.cpp: In function 'int main()':
mousetrap.cpp:73:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   73 |         freopen(file".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
mousetrap.cpp:74:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   74 |         freopen(file".out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

Subtask #1
20.0 / 20.0

# Verdict Execution time Memory Grader output
1 Correct 25 ms 47296 KB Output is correct
2 Correct 24 ms 47292 KB Output is correct
3 Correct 24 ms 47312 KB Output is correct
4 Correct 28 ms 47316 KB Output is correct
5 Correct 25 ms 47296 KB Output is correct
6 Correct 24 ms 47308 KB Output is correct
7 Correct 27 ms 47304 KB Output is correct
8 Correct 28 ms 47224 KB Output is correct
9 Correct 25 ms 47308 KB Output is correct
10 Correct 26 ms 47272 KB Output is correct

Subtask #2
25.0 / 25.0

# Verdict Execution time Memory Grader output
1 Correct 385 ms 121284 KB Output is correct
2 Correct 333 ms 113920 KB Output is correct
3 Correct 1034 ms 124724 KB Output is correct
4 Correct 523 ms 85796 KB Output is correct
5 Correct 1063 ms 124732 KB Output is correct
6 Correct 1067 ms 124856 KB Output is correct

Subtask #3
20.0 / 20.0

# Verdict Execution time Memory Grader output
1 Correct 25 ms 47296 KB Output is correct
2 Correct 24 ms 47292 KB Output is correct
3 Correct 24 ms 47312 KB Output is correct
4 Correct 28 ms 47316 KB Output is correct
5 Correct 25 ms 47296 KB Output is correct
6 Correct 24 ms 47308 KB Output is correct
7 Correct 27 ms 47304 KB Output is correct
8 Correct 28 ms 47224 KB Output is correct
9 Correct 25 ms 47308 KB Output is correct
10 Correct 26 ms 47272 KB Output is correct
11 Correct 29 ms 47316 KB Output is correct
12 Correct 30 ms 47308 KB Output is correct
13 Correct 25 ms 47372 KB Output is correct
14 Correct 26 ms 47376 KB Output is correct
15 Correct 25 ms 47444 KB Output is correct
16 Correct 26 ms 47316 KB Output is correct
17 Correct 27 ms 47308 KB Output is correct
18 Correct 25 ms 47320 KB Output is correct
19 Correct 24 ms 47292 KB Output is correct
20 Correct 24 ms 47316 KB Output is correct
21 Correct 25 ms 47308 KB Output is correct
22 Correct 29 ms 47276 KB Output is correct

Subtask #4
35.0 / 35.0

# Verdict Execution time Memory Grader output
1 Correct 25 ms 47296 KB Output is correct
2 Correct 24 ms 47292 KB Output is correct
3 Correct 24 ms 47312 KB Output is correct
4 Correct 28 ms 47316 KB Output is correct
5 Correct 25 ms 47296 KB Output is correct
6 Correct 24 ms 47308 KB Output is correct
7 Correct 27 ms 47304 KB Output is correct
8 Correct 28 ms 47224 KB Output is correct
9 Correct 25 ms 47308 KB Output is correct
10 Correct 26 ms 47272 KB Output is correct
11 Correct 385 ms 121284 KB Output is correct
12 Correct 333 ms 113920 KB Output is correct
13 Correct 1034 ms 124724 KB Output is correct
14 Correct 523 ms 85796 KB Output is correct
15 Correct 1063 ms 124732 KB Output is correct
16 Correct 1067 ms 124856 KB Output is correct
17 Correct 29 ms 47316 KB Output is correct
18 Correct 30 ms 47308 KB Output is correct
19 Correct 25 ms 47372 KB Output is correct
20 Correct 26 ms 47376 KB Output is correct
21 Correct 25 ms 47444 KB Output is correct
22 Correct 26 ms 47316 KB Output is correct
23 Correct 27 ms 47308 KB Output is correct
24 Correct 25 ms 47320 KB Output is correct
25 Correct 24 ms 47292 KB Output is correct
26 Correct 24 ms 47316 KB Output is correct
27 Correct 25 ms 47308 KB Output is correct
28 Correct 29 ms 47276 KB Output is correct
29 Correct 24 ms 47268 KB Output is correct
30 Correct 342 ms 121324 KB Output is correct
31 Correct 373 ms 121432 KB Output is correct
32 Correct 425 ms 186080 KB Output is correct
33 Correct 492 ms 217292 KB Output is correct
34 Correct 1114 ms 124824 KB Output is correct
35 Correct 1049 ms 124792 KB Output is correct
36 Correct 1042 ms 132428 KB Output is correct
37 Correct 1064 ms 132544 KB Output is correct
38 Correct 797 ms 124216 KB Output is correct
39 Correct 759 ms 124164 KB Output is correct
40 Correct 751 ms 124200 KB Output is correct