結果

問題 No.806 木を道に
ユーザー 👑 hitonanodehitonanode
提出日時 2019-03-22 21:25:15
言語 C++14
(gcc 12.3.0 + boost 1.83.0)
結果
WA  
実行時間 -
コード長 4,002 bytes
コンパイル時間 1,863 ms
コンパイル使用メモリ 184,080 KB
実行使用メモリ 15,744 KB
最終ジャッジ日時 2023-10-19 06:23:33
合計ジャッジ時間 5,032 ms
ジャッジサーバーID
（参考情報） 		judge12 / judge15
このコードへのチャレンジ
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テストケース

テストケース表示
入力 結果 実行時間
実行使用メモリ
testcase_00 AC 2 ms
4,348 KB
testcase_01 AC 2 ms
4,348 KB
testcase_02 WA -
testcase_03 WA -
testcase_04 AC 2 ms
4,348 KB
testcase_05 WA -
testcase_06 WA -
testcase_07 AC 2 ms
4,348 KB
testcase_08 AC 2 ms
4,348 KB
testcase_09 AC 2 ms
4,348 KB
testcase_10 WA -
testcase_11 WA -
testcase_12 WA -
testcase_13 WA -
testcase_14 WA -
testcase_15 WA -
testcase_16 WA -
testcase_17 WA -
testcase_18 WA -
testcase_19 WA -
testcase_20 WA -
testcase_21 WA -
testcase_22 WA -
testcase_23 WA -
testcase_24 AC 50 ms
9,536 KB
testcase_25 AC 80 ms
12,704 KB
testcase_26 AC 23 ms
7,152 KB
testcase_27 AC 85 ms
15,744 KB
testcase_28 AC 3 ms
4,348 KB
権限があれば一括ダウンロードができます

ソースコード

diff # 

#include <bits/stdc++.h>
using namespace std;
using lint = long long int;
using pint = pair<int, int>;
using plint = pair<lint, lint>;
struct fast_ios { fast_ios(){ cin.tie(0); ios::sync_with_stdio(false); cout << fixed << setprecision(20); }; } fast_ios_;
#define FOR(i, begin, end) for(int i=(begin),i##_end_=(end);i<i##_end_;i++)
#define IFOR(i, begin, end) for(int i=(end)-1,i##_begin_=(begin);i>=i##_begin_;i--)
#define REP(i, n) FOR(i,0,n)
#define IREP(i, n) IFOR(i,0,n)
template<typename T> istream &operator>>(istream &is, vector<T> &vec){ for (auto &v : vec) is >> v; return is; }
template<typename T> ostream &operator<<(ostream &os, const vector<T> &vec){ os << "["; for (auto v : vec) os << v << ","; os << "]"; return os; }
template<typename T> ostream &operator<<(ostream &os, const deque<T> &vec){ os << "deq["; for (auto v : vec) os << v << ","; os << "]"; return os; }
template<typename T> ostream &operator<<(ostream &os, const set<T> &vec){ os << "{"; for (auto v : vec) os << v << ","; os << "}"; return os; }
template<typename T> ostream &operator<<(ostream &os, const unordered_set<T> &vec){ os << "{"; for (auto v : vec) os << v << ","; os << "}"; return os; }
template<typename T> ostream &operator<<(ostream &os, const multiset<T> &vec){ os << "{"; for (auto v : vec) os << v << ","; os << "}"; return os; }
template<typename T> ostream &operator<<(ostream &os, const unordered_multiset<T> &vec){ os << "{"; for (auto v : vec) os << v << ","; os << "}"; return os; }
template<typename T1, typename T2> ostream &operator<<(ostream &os, const pair<T1, T2> &pa){ os << "(" << pa.first << "," << pa.second << ")"; return os; }
template<typename TK, typename TV> ostream &operator<<(ostream &os, const map<TK, TV> &mp){ os << "{"; for (auto v : mp) os << v.first << "=>" << v.second << ","; os << "}"; return os; }
template<typename TK, typename TV> ostream &operator<<(ostream &os, const unordered_map<TK, TV> &mp){ os << "{"; for (auto v : mp) os << v.first << "=>" << v.second << ","; os << "}"; return os; }
template<typename T> void ndarray(vector<T> &vec, int len) { vec.resize(len); }
template<typename T, typename... Args> void ndarray(vector<T> &vec, int len, Args... args) { vec.resize(len); for (auto &v : vec) ndarray(v, args...); }
template<typename T> bool mmax(T &m, const T q) { if (m < q) {m = q; return true;} else return false; }
template<typename T> bool mmin(T &m, const T q) { if (m > q) {m = q; return true;} else return false; }
template<typename T1, typename T2> pair<T1, T2> operator+(const pair<T1, T2> &l, const pair<T1, T2> &r) { return make_pair(l.first + r.first, l.second + r.second); }
template<typename T1, typename T2> pair<T1, T2> operator-(const pair<T1, T2> &l, const pair<T1, T2> &r) { return make_pair(l.first - r.first, l.second - r.second); }
#define dbg(x) cerr << #x << " = " << (x) << " (L" << __LINE__ << ") " << __FILE__ << endl;
#define FI first
#define SE second
#define ALL(x) (x).begin(), (x).end()
#define SZ(x) ((lint)(x).size())
#define POW2(n) (1LL << (n))

int N;
using Edges = map<int, vector<int>>;
vector<int> tree_distance(int N, int r, Edges &e)
{
    vector<int> res(N); // res[r] = 0;
    queue<pint> q;
    q.push(pint(r, -1)); // (now, prev)
    while (!q.empty())
    {
        pint pa = q.front();
        q.pop();
        if (pa.second >= 0)
            res[pa.first] = res[pa.second] + 1;
        for (auto nx : e[pa.first])
            if (nx != pa.second)
                q.push(pint(nx, pa.first));
    }
    return res;
}
int tree_diameter(int N, int r, Edges &e)
{
    vector<int> d = tree_distance(N, r, e);
    int s = distance(d.begin(), max_element(d.begin(), d.end()));
    d = tree_distance(N, s, e);
    return *max_element(d.begin(), d.end());
}
int main()
{
    cin >> N;
    Edges e;
    REP(_, N - 1)
    {
        int a, b;
        cin >> a >> b;
        e[a - 1].push_back(b - 1);
        e[b - 1].push_back(a - 1);
    }
    int dia = tree_diameter(N, 0, e);
    cout << N - 1 - dia << endl;
}
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