結果

問題 No.1976 Cut then Connect
ユーザー magsta
提出日時 2022-06-08 19:58:47
言語 C++14
(gcc 13.3.0 + boost 1.87.0)
結果
AC  
実行時間 123 ms / 2,000 ms
コード長 3,371 bytes
コンパイル時間 7,100 ms
コンパイル使用メモリ 306,836 KB
実行使用メモリ 31,832 KB
最終ジャッジ日時 2024-11-24 12:13:55
合計ジャッジ時間 9,605 ms
ジャッジサーバーID
(参考情報)
judge5 / judge2
このコードへのチャレンジ
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ファイルパターン 結果
sample AC * 2
other AC * 31
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 #
プレゼンテーションモードにする

#include <bits/stdc++.h>
#include "testlib.h"
using namespace std;
struct Edge {
int u;
int v;
Edge(int a, int b) : u(a), v(b) {
}
};
using Graph = vector<vector<Edge>>;
vector<vector<int>> dp, dp2, dp_;
void dfs(const Graph& G, int v, int p) {
for (auto nv : G[v]) {
if (nv.v == p) continue;
dfs(G, nv.v, v);
}
int count_ = -1;
for (auto c : G[v]) {
count_++;
if (c.v == p) continue;
int count = -1;
for (auto d : G[c.v]) {
count++;
if (d.v == v) continue;
//cout << v << " " << c.v << " " << d.v << " " << count << " " << count_ << endl;
if (dp[v][count_] < dp[c.v][count] + 1) {
dp2[v][count_] = dp[v][count_];
dp[v][count_] = dp[c.v][count] + 1;
}
else if (dp2[v][count_] < dp[c.v][count] + 1) {
dp2[v][count_] = dp[c.v][count] + 1;
}
}
count = -1;
dp_[v][count_] = dp[v][count_] + dp2[v][count_];
for (auto d : G[c.v]) {
count++;
if (d.v == v) continue;
dp_[v][count_] = max(dp_[v][count_], dp_[c.v][count]);
}
}
}
void dfs2(const Graph& G, int v, int p) {
int count_ = -1;
for (auto c : G[v]) {
count_++;
if (c.v == p) {
int count = -1;
for (auto d : G[c.v]) {
count++;
if (d.v == v) continue;
if (dp[v][count_] < dp[c.v][count] + 1) {
dp2[v][count_] = dp[v][count_];
dp[v][count_] = dp[c.v][count] + 1;
}
else if (dp2[v][count_] < dp[c.v][count] + 1) {
dp2[v][count_] = dp[c.v][count] + 1;
}
}
count = -1;
dp_[v][count_] = dp[v][count_] + dp2[v][count_];
for (auto d : G[c.v]) {
count++;
if (d.v == v) continue;
dp_[v][count_] = max(dp_[v][count_], dp_[c.v][count]);
}
}
}
for (auto nv : G[v]) {
if (nv.v == p) continue;
dfs2(G, nv.v, v);
}
}
int main() {
registerValidation();
int N = inf.readInt(2, 100000, "N");
inf.readEoln();
Graph G(N);
vector<int> a(N - 1), b(N - 1), c(N - 1), d(N - 1);
for (int i = 0; i < N - 1; i++) {
a[i] = inf.readInt(1, N, "a");
inf.readSpace();
b[i] = inf.readInt(1, N, "a");
inf.readEoln();
c[i] = G[a[i] - 1].size();
d[i] = G[b[i] - 1].size();
G[a[i] - 1].emplace_back(a[i] - 1, b[i] - 1);
G[b[i] - 1].emplace_back(b[i] - 1, a[i] - 1);
}
inf.readEof();
for (int i = 0; i < N; i++) {
if (G[i].size() == 0) cout << -1 << endl;
}
dp.assign(N, vector<int>(0));
dp2.assign(N, vector<int>(0));
dp_.assign(N, vector<int>(0));
for (int i = 0; i < N; i++) {
dp[i].assign(G[i].size(), 0);
dp2[i].assign(G[i].size(), 0);
dp_[i].assign(G[i].size(), 0);
}
dfs(G, 0, -1);
dfs2(G, 0, -1);
int ans_ = 1000000;
for (int i = 0; i < N - 1; i++) {
ans_ = min(ans_, max(max(dp_[a[i] - 1][c[i]], dp_[b[i] - 1][d[i]]), (dp_[a[i] - 1][c[i]] + 1) / 2 + (dp_[b[i] - 1][d[i]] + 1) / 2 + 1));
}
cout << ans_ << endl;
}
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