#include <bits/stdc++.h> using namespace std; typedef long long LL; typedef long double LD; typedef pair < int, int > PII; typedef pair < LL, LL > PLL; typedef pair < LD, LD > PDD; #define _upgrade ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0); #define all(x) (x).begin(), (x).end() #define sz(x) (int)(x).size() template < typename _T > inline void _DBG(const char *s, _T x) { cerr << s << " = " << x << "\n"; } template < typename _T, typename... args > void _DBG(const char *s, _T x, args... a) { while(*s != ',') cerr << *s++; cerr << " = " << x << ','; _DBG(s + 1, a...); } #ifdef LOCAL #define DBG(...) _DBG(#__VA_ARGS__, __VA_ARGS__) #define __gcd gcd #else #define DBG(...) (__VA_ARGS__) #define cerr if(0) cout #endif // ********************** CODE ********************** // const int N = 303; int n, m, k, dp[N], last[N], mn; bool already[N][N]; vector < int > G[N]; bool blocked[N]; vector < int > get() { bool flag = false; vector < int > ans; for(int v = 1; v <= n; v++) { dp[v] = last[v] = 0; if(blocked[v]) { dp[v] = -1; continue; } flag = true; for(auto u: G[v]) { if(!blocked[u] && dp[v] < dp[u] + 1) { dp[v] = dp[u] + 1; last[v] = u; } } } if(!flag) { return ans; } int id = max_element(dp + 1, dp + n + 1) - dp; while(id != 0) { ans.push_back(id); id = last[id]; } return ans; } void Go(int x) { vector < int > vec = get(); mn = min(mn, sz(vec)); if(x == 0) return; for(auto v: vec) { blocked[v] = true; Go(x - 1); blocked[v] = false; } } int main() { _upgrade cin >> n >> m >> k; mn = n + 7; for(int i = 0; i < m; i++) { int a, b; cin >> a >> b; if(already[a][b]) continue; already[a][b] = true; G[b].push_back(a); } Go(k); cout << mn << "\n"; return 0; }
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 | #include <bits/stdc++.h> using namespace std; typedef long long LL; typedef long double LD; typedef pair < int, int > PII; typedef pair < LL, LL > PLL; typedef pair < LD, LD > PDD; #define _upgrade ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0); #define all(x) (x).begin(), (x).end() #define sz(x) (int)(x).size() template < typename _T > inline void _DBG(const char *s, _T x) { cerr << s << " = " << x << "\n"; } template < typename _T, typename... args > void _DBG(const char *s, _T x, args... a) { while(*s != ',') cerr << *s++; cerr << " = " << x << ','; _DBG(s + 1, a...); } #ifdef LOCAL #define DBG(...) _DBG(#__VA_ARGS__, __VA_ARGS__) #define __gcd gcd #else #define DBG(...) (__VA_ARGS__) #define cerr if(0) cout #endif // ********************** CODE ********************** // const int N = 303; int n, m, k, dp[N], last[N], mn; bool already[N][N]; vector < int > G[N]; bool blocked[N]; vector < int > get() { bool flag = false; vector < int > ans; for(int v = 1; v <= n; v++) { dp[v] = last[v] = 0; if(blocked[v]) { dp[v] = -1; continue; } flag = true; for(auto u: G[v]) { if(!blocked[u] && dp[v] < dp[u] + 1) { dp[v] = dp[u] + 1; last[v] = u; } } } if(!flag) { return ans; } int id = max_element(dp + 1, dp + n + 1) - dp; while(id != 0) { ans.push_back(id); id = last[id]; } return ans; } void Go(int x) { vector < int > vec = get(); mn = min(mn, sz(vec)); if(x == 0) return; for(auto v: vec) { blocked[v] = true; Go(x - 1); blocked[v] = false; } } int main() { _upgrade cin >> n >> m >> k; mn = n + 7; for(int i = 0; i < m; i++) { int a, b; cin >> a >> b; if(already[a][b]) continue; already[a][b] = true; G[b].push_back(a); } Go(k); cout << mn << "\n"; return 0; } |