oj.uz

답안 #571620

# 제출 시각 아이디 문제 언어 결과 실행 시간 메모리
571620 2022-06-02T12:23:24 Z piOOE Mousetrap (CEOI17_mousetrap) C++17
45 / 100
 696 ms 68404 KB 
#include <bits/stdc++.h>

using namespace std;

#define sz(x) ((int)size(x))
#define all(x) begin(x), end(x)
#define trace(x) cout << #x << ": " << (x) << endl;

typedef long long ll;

mt19937 rnd(chrono::steady_clock::now().time_since_epoch().count());

int rand(int l, int r) { return (int) ((ll) rnd() % (r - l + 1)) + l; }

template<typename T>
bool ckmn(T &x, T y) {
    if (x > y) {
        x = y;
        return true;
    }
    return false;
}

template<typename T>
bool ckmx(T &x, T y) {
    if (x < y) {
        x = y;
        return true;
    }
    return false;
}

const int N = 1000001, infI = 1e9 + 7;
const ll infL = 3e18;

int n, t, m;
vector<int> g[N];
int dp[N], parent[N];
vector<int> tops;

void dfs(int v, int p) {
    parent[v] = p;
    int mx1 = 0, mx2 = 0, cnt = 0;
    for (int to: g[v]) {
        if (to != p) {
            ++cnt;
            dfs(to, v);
            if (mx1 < dp[to]) {
                mx2 = mx1;
                mx1 = dp[to];
            } else if (mx2 < dp[to]) {
                mx2 = dp[to];
            }
        }
    }
    dp[v] = mx2 + cnt;
    tops.push_back(v);
}


int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    cin >> n >> t >> m;
    --t, --m;
    if (t == m) {
        exit(1);
    }
    for (int i = 1; i < n; ++i) {
        int a, b;
        cin >> a >> b;
        --a, --b;
        g[a].push_back(b);
        g[b].push_back(a);
    }
    dfs(t, t);
    int l = -1, r = infI;
    while (l + 1 < r) {
        int mid = (l + r) >> 1;
        int total = 0;
        {
            int x = m;
            int prv = 0;
            while (x != t) {
                for (int to : g[x]) {
                    if (to != prv && to != parent[x])
                        ++total;
                }
                prv = x;
                x = parent[x];
            }
        }
        int x = m, prv = -1;
        bool ok = total <= mid;
        int can = 0;
        while (ok && x != t) {
            ++can;
            int cnt = 0;
            int nw = 0;
            for (int to: g[x]) {
                if (to != parent[x] && to != prv) {
                    if (dp[to] + total > mid) {
                        ++cnt;
                    } else {
                        ++nw;
                    }
                }
            }
            total -= nw;
            if (cnt > can) {
                ok = false;
            }
            prv = x;
            x = parent[x];
        }
        if (ok) {
            r = mid;
        } else {
            l = mid;
        }
    }
    cout << r;
    return 0;
}

Subtask #1
20.0 / 20.0

# 결과 실행 시간 메모리 Grader output
1 Correct 13 ms 23816 KB Output is correct
2 Correct 12 ms 23792 KB Output is correct
3 Correct 12 ms 23800 KB Output is correct
4 Correct 12 ms 23764 KB Output is correct
5 Correct 12 ms 23764 KB Output is correct
6 Correct 12 ms 23764 KB Output is correct
7 Correct 12 ms 23744 KB Output is correct
8 Correct 12 ms 23764 KB Output is correct
9 Correct 12 ms 23764 KB Output is correct
10 Correct 15 ms 23828 KB Output is correct

Subtask #2
25.0 / 25.0

# 결과 실행 시간 메모리 Grader output
1 Correct 320 ms 66948 KB Output is correct
2 Correct 243 ms 62684 KB Output is correct
3 Correct 668 ms 68296 KB Output is correct
4 Correct 286 ms 46016 KB Output is correct
5 Correct 696 ms 68404 KB Output is correct
6 Correct 658 ms 68208 KB Output is correct

Subtask #3
0 / 20.0

# 결과 실행 시간 메모리 Grader output
1 Correct 13 ms 23816 KB Output is correct
2 Correct 12 ms 23792 KB Output is correct
3 Correct 12 ms 23800 KB Output is correct
4 Correct 12 ms 23764 KB Output is correct
5 Correct 12 ms 23764 KB Output is correct
6 Correct 12 ms 23764 KB Output is correct
7 Correct 12 ms 23744 KB Output is correct
8 Correct 12 ms 23764 KB Output is correct
9 Correct 12 ms 23764 KB Output is correct
10 Correct 15 ms 23828 KB Output is correct
11 Incorrect 12 ms 23764 KB Output isn't correct
12 Halted 0 ms 0 KB -

Subtask #4
0 / 35.0

# 결과 실행 시간 메모리 Grader output
1 Correct 13 ms 23816 KB Output is correct
2 Correct 12 ms 23792 KB Output is correct
3 Correct 12 ms 23800 KB Output is correct
4 Correct 12 ms 23764 KB Output is correct
5 Correct 12 ms 23764 KB Output is correct
6 Correct 12 ms 23764 KB Output is correct
7 Correct 12 ms 23744 KB Output is correct
8 Correct 12 ms 23764 KB Output is correct
9 Correct 12 ms 23764 KB Output is correct
10 Correct 15 ms 23828 KB Output is correct
11 Correct 320 ms 66948 KB Output is correct
12 Correct 243 ms 62684 KB Output is correct
13 Correct 668 ms 68296 KB Output is correct
14 Correct 286 ms 46016 KB Output is correct
15 Correct 696 ms 68404 KB Output is correct
16 Correct 658 ms 68208 KB Output is correct
17 Incorrect 12 ms 23764 KB Output isn't correct
18 Halted 0 ms 0 KB -