結果

問題 No.2565 はじめてのおつかい
ユーザー lemon_math_tea
提出日時 2023-12-02 16:49:27
言語 C++17
(gcc 13.3.0 + boost 1.87.0)
結果
AC  
実行時間 101 ms / 2,000 ms
コード長 4,465 bytes
コンパイル時間 4,614 ms
コンパイル使用メモリ 262,744 KB
最終ジャッジ日時 2025-02-18 05:41:23
ジャッジサーバーID
(参考情報)
judge2 / 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 * 3
other AC * 50
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

// ctrl + shift + B
#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
#define ll long long
#define all(x) (x).begin(), (x).end()
#define yes "Yes"
#define no "No"
//  O(log(N))
template<typename T>
T gcd(T a, T b) {
if (b == 0) return a;
else return gcd(b, a % b);
}
//  O(sqrt(N))
bool is_prime(ll n) {
for (ll i = 2; i*i <= n; i++) {
if (n % i == 0) return false;
}
return true;
}
//n O(Nloglog(N))
vector<ll> getprime(ll n) {
vector<ll> ans;
vector<bool> isprime(n + 1, true);
//0, 1
isprime[0] = false; isprime[1] = false;
//
for (int i = 2; i <= n; i++) {
if (!isprime[i]) continue;
ans.push_back(i);
for (int j = 2 * i; j <= n; j += i) {
//ii
isprime[j] = false;
}
}
return ans;
}
// n O(sqrt(N))
vector<pair<ll, ll>> prime_factorize(ll n) {
vector<pair<ll, ll>> ans;
for (ll i = 2; i*i <= n; i++) {
if (n % i != 0) continue;
ll e = 0;
while (n % i == 0) {
e++;
n /= i;
}
ans.push_back({i, e});
}
if (n != 1) ans.push_back({n, 1});
return ans;
}
// n O(NlogN)
vector<ll> smallest_prime(ll n) {
vector<ll> spf(n+1);
for (ll i = 0; i <= n; i++) spf[i] = i; //
for (ll i = 2; i+i <= n; i++) {
if (spf[i] == i) {
for (ll j = i*i; j <= n; j += i) {
if (spf[j] == j) spf[j] = i;
}
}
}
return spf;
}
//
// using mint = modint998244353;
using mint = modint1000000007;
int main() {
int n, m; cin >> n >> m;
vector<vector<int>> e(n);
for (int i = 0; i < m; i++) {
int u, v; cin >> u >> v;
u--; v--;
e[u].push_back(v);
}
ll INF = 1e18;
vector<ll> iki(n, INF);
iki[0] = 0;
queue<int> q;
q.push(0);
vector<bool> seen(n);
seen[0] = true;
while (q.size()) {
int u = q.front(); q.pop();
for (auto v : e[u]) {
if (seen[v]) continue;
seen[v] = true;
iki[v] = iki[u] + 1;
q.push(v);
}
}
bool a = seen[n-2];
bool b = seen[n-1];
int ans = -1;
if (a) {
bool f = true;
int now = iki[n-2];
q.push(n-2);
vector<bool> seen(n);
seen[n-2] = true;
vector<int> d(n);
while (q.size()) {
int u = q.front(); q.pop();
for (auto v : e[u]) {
if (seen[v]) continue;
seen[v] = true;
d[v] = d[u] + 1;
q.push(v);
}
}
if (seen[n-1]) now += d[n-1];
else f = false;
q.push(n-1);
vector<bool> seen1(n);
seen[n-1] = true;
vector<int> d1(n);
while (q.size()) {
int u = q.front(); q.pop();
for (auto v : e[u]) {
if (seen1[v]) continue;
seen1[v] = true;
d1[v] = d1[u] + 1;
q.push(v);
}
}
if (seen1[0]) now += d1[0];
else f = false;
if (f) ans = now;
}
if (b) {
bool f = true;
int now = iki[n-1];
q.push(n-1);
vector<bool> seen(n);
seen[n-1] = true;
vector<int> di(n);
while (q.size()) {
int u = q.front(); q.pop();
for (auto v : e[u]) {
if (seen[v]) continue;
seen[v] = true;
di[v] = di[u] + 1;
q.push(v);
}
}
if (seen[n-2]) now += di[n-2];
else f = false;
q.push(n-2);
vector<bool> seen1(n);
seen[n-2] = true;
vector<int> di1(n);
while (q.size()) {
int u = q.front(); q.pop();
for (auto v : e[u]) {
if (seen1[v]) continue;
seen1[v] = true;
di1[v] = di1[u] + 1;
q.push(v);
}
}
if (seen1[0]) now += di1[0];
else f = false;
if (f) {
if (ans < 0) ans = now;
else ans = min(ans, now);
}
}
cout << ans << endl;
}
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