#define _CRT_SECURE_NO_WARNINGS
#include <bits/stdc++.h>
//#include "temp.cpp"
#include <cstdio>
using namespace std;
#ifndef ONLINE_JUDGE
#define dbg(x) cerr << #x <<" "; print(x); cerr << endl;
#else
#define dbg(x)
#endif
#define sz(x) (int((x).size()))
#define len(x) (int)x.length()
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
#define clr(x) (x).clear()
#define uniq(x) x.resize(unique(all(x)) - x.begin());
#define blt __builtin_popcount
#define pb push_back
#define popf pop_front
#define popb pop_back
#define ld long double
#define ll long long
void print(long long t) {cerr << t;}
void print(int t) {cerr << t;}
void print(string t) {cerr << t;}
void print(char t) {cerr << t;}
void print(double t) {cerr << t;}
void print(unsigned long long t) {cerr << t;}
void print(long double t) {cerr << t;}
template <class T, class V> void print(pair <T, V> p);
template <class T> void print(vector <T> v);
template <class T> void print(set <T> v);
template <class T, class V> void print(map <T, V> v);
template <class T> void print(multiset <T> v);
template <class T> void print(T v[],T n) {cerr << "["; for(int i = 0; i < n; i++) {cerr << v[i] << " ";} cerr << "]";}
template <class T, class V> void print(pair <T, V> p) {cerr << "{"; print(p.first); cerr << ","; print(p.second); cerr << "}";}
template <class T> void print(vector <T> v) {cerr << "[ "; for (T i : v) {print(i); cerr << " ";} cerr << "]";}
template <class T> void print(set <T> v) {cerr << "[ "; for (T i : v) {print(i); cerr << " ";} cerr << "]";}
template <class T> void print(multiset <T> v) {cerr << "[ "; for (T i : v) {print(i); cerr << " ";} cerr << "]";}
template <class T, class V> void print(map <T, V> v) {cerr << "[ "; for (auto i : v) {print(i); cerr << " ";} cerr << "]";}
#include <ext/pb_ds/assoc_container.hpp>
using namespace __gnu_pbds;
#define nl '\n'
// for grid problems
int dx[8] = {-1,0,1,0,1,-1,1,-1};
int dy[8] = {0,1,0,-1,1,1,-1,-1};
// lowest / (1 << 17) >= 1e5 / (1 << 18) >= 2e5 / (1 << 21) >= 1e6
void fastIO() {
ios_base::sync_with_stdio(false);
cin.tie(nullptr); cout.tie(nullptr);
}
// file in/out
void setIO(string str = "") {
fastIO();
if (str != "") {
freopen((str + ".in").c_str(), "r", stdin);
freopen((str + ".out").c_str(), "w", stdout);
}
}
// Indexed Set
template <class T> using Tree = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
const int N = 5e5 + 10, inf = 1e9;
int n, k, in[N], dist[N], answ;
vector<int> adj[N];
bool used[N];
int cycle(int node) {
// dbg(node)
int cur = node;
vector<int> path;
while(!used[cur]) {
used[cur] = true;
path.push_back(cur);
cur = adj[cur][0];
}
// dbg(path)
// dbg(sz(path))
for(auto i: path) {
used[i] = false;
}
{
priority_queue<pair<int, int>, vector<pair<int, int>>, greater<pair<int, int>> > q;
for(auto i: path) {
q.push({dist[i], i});
}
while(!q.empty()) {
auto u = q.top();
q.pop();
if(used[u.second]) {
continue;
}
used[u.second] = true;
if(u.first >= k) {
break;
}
for(auto i: adj[u.second]) {
if(dist[i] > dist[u.second] + 1) {
dist[i] = dist[u.second] + 1;
q.push({dist[i], i});
}
}
}
}
int m = sz(path);
int mini = 0;
for(int i = 0; i < m; i++) {
if(dist[path[i]] == inf) {
++mini;
}
}
if(!mini) {
for(auto i: path) {
used[i] = true;
}
return 0;
}
// dbg("done")
int lst = -1;
vector<int> ptr(m, 0);
for(int i = 2 * m - 1; i >= 0; i--) {
if(dist[path[i % m]] == inf) {
lst = i % m;
ptr[lst] = lst;
} else if(lst != -1) {
// assert(lst != -1);
ptr[i % m] = lst;
}
}
// dbg(ptr)
for(int start = 0; start < min(k, m); start++) {
int road = 0, pos = start, ansi = 0;
// dbg(start)
while(true) {
if(ptr[pos] < pos) {
road += ptr[pos] + m - pos;
} else {
road += ptr[pos] - pos;
}
pos = ptr[pos];
if(road >= m) {
break;
}
ansi++, road += k;
pos += k, pos %= m;
}
// assert(false);
mini = min(mini, ansi);
}
//
for(auto i: path) {
used[i] = true;
}
return mini;
}
void solve_() {
cin >> n >> k;
for(int i = 1; i <= n; i++) {
int a, b; cin >> a >> b;
adj[a].push_back(b); in[b]++;
}
for(int i = 2; i <= n; i++) {
if(!in[i]) {
adj[1].push_back(i);
in[i]++;
answ++;
}
}
{
for(int i = 1; i <= n; i++) {
dist[i] = inf;
}
queue<pair<int, int>> q;
q.push({1, 0});
dist[1] = 0;
used[1] = true;
while(!q.empty()) {
auto u = q.front();
q.pop();
// dbg(u)
if(u.second > k) {
dist[u.first] = 1;
answ++;
}
for(auto i: adj[u.first]) {
in[i]--;
dist[i] = min(dist[i], dist[u.first] + 1);
if(!in[i]) {
used[i] = true;
q.push({i, dist[i]});
}
}
}
}
// for(int i = 1; i <= n; i++) {
// dbg(dist[i])
// }
// dbg(answ)
for(int i = 1; i <= n; i++) {
if(!used[i]) {
answ += cycle(i);
}
}
printf("%d\n", answ);
}
int main () {
setIO("");
auto solve = [&](int test_case)-> void {
while(test_case--) {
solve_();
}
};
int test_cases = 1;
solve(test_cases);
return 0;
}
Compilation message
link.cpp: In function 'void setIO(std::string)':
link.cpp:65:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
65 | freopen((str + ".in").c_str(), "r", stdin);
| ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
link.cpp:66:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
66 | freopen((str + ".out").c_str(), "w", stdout);
| ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Correct |
8 ms |
11988 KB |
Output is correct |
| 2 |
Correct |
7 ms |
11988 KB |
Output is correct |
| 3 |
Correct |
7 ms |
12116 KB |
Output is correct |
| 4 |
Correct |
8 ms |
12116 KB |
Output is correct |
| 5 |
Correct |
8 ms |
12244 KB |
Output is correct |
| 6 |
Correct |
15 ms |
13364 KB |
Output is correct |
| 7 |
Correct |
21 ms |
14164 KB |
Output is correct |
| 8 |
Correct |
29 ms |
15108 KB |
Output is correct |
| 9 |
Correct |
54 ms |
16564 KB |
Output is correct |
| 10 |
Correct |
40 ms |
16484 KB |
Output is correct |
| 11 |
Correct |
107 ms |
19656 KB |
Output is correct |
| 12 |
Correct |
114 ms |
20220 KB |
Output is correct |
| 13 |
Correct |
133 ms |
23008 KB |
Output is correct |
| 14 |
Correct |
155 ms |
24880 KB |
Output is correct |
| 15 |
Correct |
237 ms |
27548 KB |
Output is correct |
| 16 |
Correct |
269 ms |
29576 KB |
Output is correct |
| 17 |
Correct |
325 ms |
32000 KB |
Output is correct |
| 18 |
Correct |
342 ms |
33192 KB |
Output is correct |
| 19 |
Correct |
322 ms |
33384 KB |
Output is correct |
| 20 |
Correct |
368 ms |
33300 KB |
Output is correct |
| 21 |
Correct |
330 ms |
33624 KB |
Output is correct |
| 22 |
Correct |
386 ms |
34040 KB |
Output is correct |
| 23 |
Correct |
309 ms |
33568 KB |
Output is correct |
| 24 |
Correct |
332 ms |
34012 KB |
Output is correct |
| 25 |
Correct |
350 ms |
34076 KB |
Output is correct |
