oj.uz

답안 #1028574

# 제출 시각 아이디 문제 언어 결과 실행 시간 메모리
1028574 2024-07-20T05:12:58 Z Thanhs Mousetrap (CEOI17_mousetrap) C++14
25 / 100
 510 ms 71980 KB 
#pragma GCC optimize("Ofast")
#pragma GCC optimize("unroll-loops")
#include <bits/stdc++.h>
using namespace std;
// #define int long long
// #define double long double
 
#define endl '\n'
#define fastIO ios_base::sync_with_stdio(false); cin.tie(nullptr); cout.tie(nullptr);
#define setmin(x, y) x = min((x), (y))
#define setmax(x, y) x = max((x), (y))
#define sqr(x) ((x) * (x))
#define fi first
#define se second
 
// mt19937 hdp(chrono::high_resolution_clock::now().time_since_epoch().count());
// int rand(int l, int r){return l + ((hdp() % (r - l + 1)) + r - l + 1) % (r - l + 1);}
 
const int NM = 1e6 + 5;
const int mod = 1e6 + 3;
const int inf = 1e9 + 1;

vector<int> g[NM];
int n, t, m, w[NM], W[NM], dep[NM], par[NM];
vector<pair<int, int>> L;

void dfs(int u = t, int p = 0)
{
    if (u != t)
        W[u] = W[par[u]] + max(0, (int)g[u].size() - 2);
    int be = 0, sb = 0;
    for (auto v : g[u])
    {
        if (v == p)
            continue;
        dep[v] = dep[u] + 1;
        par[v] = u;
        dfs(v, u);
        if (be < w[v])
        {
            sb = be;
            be = w[v];
        }
        else if (sb < w[v])
            sb = w[v];
    }
    if (g[u].size() - !!p == 0)
        w[u] = 0;
    else if (g[u].size() - !!p == 1)
        w[u] = 1;
    else 
        w[u] += sb + g[u].size() - !!p;
}

bool check(int x)
{
    int B = 0;
    for (auto p : L)
        if (p.se + B > x)
        {
            if (B > p.fi)
                return false;
            B++;
        }
    return true;
}

signed main()
{
    if (fopen("in.txt", "r")) {
        freopen("in.txt", "r", stdin);
        freopen("out.txt", "w", stdout);
    }
    fastIO
    cin >> n >> t >> m;
    for (int i = 2; i <= n; i++)
    {
        int u, v;
        cin >> u >> v;
        g[u].push_back(v);
        g[v].push_back(u);
    }
    dfs();
    int u = m, prv = 0;
    while (u != t)
    {
        for (auto v : g[u])
            if (v != prv)
                L.emplace_back(dep[m] - dep[u], w[v] + W[par[v]] + (!prv));
        prv = u;
        u = par[u];
    }
    sort(L.begin(), L.end());
    int l = -1, r = 2 * n;
    while (l < r - 1)
    {
        int mid = l + r >> 1;
        if (check(mid))
            r = mid;
        else
            l = mid;
    }
    cout << r;
}

Compilation message

mousetrap.cpp: In function 'int main()':
mousetrap.cpp:97:21: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   97 |         int mid = l + r >> 1;
      |                   ~~^~~
mousetrap.cpp:71:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   71 |         freopen("in.txt", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~
mousetrap.cpp:72:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   72 |         freopen("out.txt", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~

Subtask #1
0 / 20.0

# 결과 실행 시간 메모리 Grader output
1 Incorrect 11 ms 23896 KB Output isn't correct
2 Halted 0 ms 0 KB -

Subtask #2
25.0 / 25.0

# 결과 실행 시간 메모리 Grader output
1 Correct 180 ms 70728 KB Output is correct
2 Correct 156 ms 66128 KB Output is correct
3 Correct 496 ms 71764 KB Output is correct
4 Correct 187 ms 47916 KB Output is correct
5 Correct 455 ms 71752 KB Output is correct
6 Correct 510 ms 71980 KB Output is correct

Subtask #3
0 / 20.0

# 결과 실행 시간 메모리 Grader output
1 Incorrect 11 ms 23896 KB Output isn't correct
2 Halted 0 ms 0 KB -

Subtask #4
0 / 35.0

# 결과 실행 시간 메모리 Grader output
1 Incorrect 11 ms 23896 KB Output isn't correct
2 Halted 0 ms 0 KB -