Submission #640021

#	Time	Username	Problem	Language	Result	Execution time	Memory
640021		IWTIM	Mag (COCI16_mag)	C++17	24 / 120	141 ms	55984 KiB

mag

# include <bits/stdc++.h>
using namespace std;
using ll = long long;
using db = long double; // or double, if TL is tight
using str = string; // yay python! 
 
// pairs
using pii = pair<int,int>;
using pl = pair<ll,ll>;
using pd = pair<db,db>;
#define mp make_pair
#define f first
#define s second
 
#define tcT template<class T
#define tcTU tcT, class U
// ^ lol this makes everything look weird but I'll try it
tcT> using V = vector<T>; 
tcT, size_t SZ> using AR = array<T,SZ>; 
using vi = V<int>;
using vb = V<bool>;
using vl = V<ll>;
using vd = V<db>;
using vs = V<str>;
using vpi = V<pii>;
using vpl = V<pl>;
using vpd = V<pd>;
 
// vectors
// oops size(x), rbegin(x), rend(x) need C++17
#define sz(x) int((x).size())
#define bg(x) begin(x)
#define all(x) bg(x), end(x)
#define rall(x) x.rbegin(), x.rend() 
#define sor(x) sort(all(x)) 
#define rsz resize
#define ins insert 
#define pb push_back
#define eb emplace_back
#define ft front()
#define bk back()
 
#define lb lower_bound
#define ub upper_bound
#define FOR(i,a,b) for (int i = (a); i < (b); ++i)
#define F0R(i,a) FOR(i,0,a)
#define ROF(i,a,b) for (int i = (b)-1; i >= (a); --i)
#define R0F(i,a) ROF(i,0,a)
#define rep(a) F0R(_,a)
#define each(a,x) for (auto& a: x)
const int MOD = 998244353;
const int MX = 2e5+5;
const ll BIG = 1e18; // not too close to LLONG_MAX
const db PI = acos((db)-1);
const int dx[4]{1,0,-1,0}, dy[4]{0,1,0,-1}; // for every grid problem!!
mt19937 rng((uint32_t)chrono::steady_clock::now().time_since_epoch().count()); 
template<class T> using pqg = priority_queue<T,vector<T>,greater<T>>;
struct DSU {
	vi e; void init(int N) { e = vi(N,-1); }
	int get(int x) { return e[x] < 0 ? x : e[x] = get(e[x]); } 
	bool sameSet(int a, int b) { return get(a) == get(b); }
	int size(int x) { return -e[get(x)]; }
	bool unite(int x, int y) { // union by size
		x = get(x), y = get(y); if (x == y) return 0;
		if (e[x] > e[y]) swap(x,y);
		e[x] += e[y]; e[y] = x; return 1;
	}
};
/*
inline namespace Helpers {
	//////////// is_iterable
	// https://stackoverflow.com/questions/13830158/check-if-a-variable-type-is-iterable
	// this gets used only when we can call begin() and end() on that type
	tcT, class = void> struct is_iterable : false_type {};
	tcT> struct is_iterable<T, void_t<decltype(begin(declval<T>())),
	                                  decltype(end(declval<T>()))
	                                 >
	                       > : true_type {};
	tcT> constexpr bool is_iterable_v = is_iterable<T>::value;
 
	//////////// is_readable
	tcT, class = void> struct is_readable : false_type {};
	tcT> struct is_readable<T,
	        typename std::enable_if_t<
	            is_same_v<decltype(cin >> declval<T&>()), istream&>
	        >
	    > : true_type {};
	tcT> constexpr bool is_readable_v = is_readable<T>::value;
 
	//////////// is_printable
	// // https://nafe.es/posts/2020-02-29-is-printable/
	tcT, class = void> struct is_printable : false_type {};
	tcT> struct is_printable<T,
	        typename std::enable_if_t<
	            is_same_v<decltype(cout << declval<T>()), ostream&>
	        >
	    > : true_type {};
	tcT> constexpr bool is_printable_v = is_printable<T>::value;
}*/
using ll = long long;
using db = long double; // or double, if TL is tight
using str = string; // yay python! 
 
// pairs
using pii = pair<int,int>;
using pl = pair<ll,ll>;
using pd = pair<db,db>;
#define mp make_pair
#define f first
#define s second
 
#define tcT template<class T
#define tcTU tcT, class U
// ^ lol this makes everything look weird but I'll try it
tcT> using V = vector<T>; 
tcT, size_t SZ> using AR = array<T,SZ>; 
using vi = V<int>;
using vb = V<bool>;
using vl = V<ll>;
using vd = V<db>;
using vs = V<str>;
using vpi = V<pii>;
using vpl = V<pl>;
using vpd = V<pd>;
 
// vectors
// oops size(x), rbegin(x), rend(x) need C++17
#define sz(x) int((x).size())
#define bg(x) begin(x)
#define all(x) bg(x), end(x)
#define rall(x) x.rbegin(), x.rend() 
#define sor(x) sort(all(x)) 
#define rsz resize
#define ins insert 
#define pb push_back
#define eb emplace_back
#define ft front()
#define bk back()
 
#define lb lower_bound
#define ub upper_bound
#define FOR(i,a,b) for (int i = (a); i < (b); ++i)
#define F0R(i,a) FOR(i,0,a)
#define ROF(i,a,b) for (int i = (b)-1; i >= (a); --i)
#define R0F(i,a) ROF(i,0,a)
#define rep(a) F0R(_,a)
#define each(a,x) for (auto& a: x)
template<class T> using pqg = priority_queue<T,vector<T>,greater<T>>;
 
/*
inline namespace Helpers {
	//////////// is_iterable
	// https://stackoverflow.com/questions/13830158/check-if-a-variable-type-is-iterable
	// this gets used only when we can call begin() and end() on that type
	tcT, class = void> struct is_iterable : false_type {};
	tcT> struct is_iterable<T, void_t<decltype(begin(declval<T>())),
	                                  decltype(end(declval<T>()))
	                                 >
	                       > : true_type {};
	tcT> constexpr bool is_iterable_v = is_iterable<T>::value;
 
	//////////// is_readable
	tcT, class = void> struct is_readable : false_type {};
	tcT> struct is_readable<T,
	        typename std::enable_if_t<
	            is_same_v<decltype(cin >> declval<T&>()), istream&>
	        >
	    > : true_type {};
	tcT> constexpr bool is_readable_v = is_readable<T>::value;
 
	//////////// is_printable
	// // https://nafe.es/posts/2020-02-29-is-printable/
	tcT, class = void> struct is_printable : false_type {};
	tcT> struct is_printable<T,
	        typename std::enable_if_t<
	            is_same_v<decltype(cout << declval<T>()), ostream&>
	        >
	    > : true_type {};
	tcT> constexpr bool is_printable_v = is_printable<T>::value;
}*/
const int N = 3e5 + 5;
int t,n,a[N],val[N],topar[N],mx[N],answ,answ1;
vector <int> v[N];
void dfs(int a, int p) {
	int ff = (val[a] == 1);
	mx[a] = (val[a] == 1);
	for (int to : v[a]) {
		if (to == p) continue;
		dfs(to,a);
		mx[a] = max(mx[a], mx[to] + 1);
	}
	if (!ff)
	mx[a] = 0;
}
void dfs1(int a, int p){
	int mx1 = 0, mx2 = 0;
	int ff = (val[a] == 1);
	if (val[a] != 1) topar[a] = 0;
	else topar[a] = max(topar[a],1);
	for (int to : v[a]) {
		if (to == p) continue;
		if(mx[to] >= mx1) {
			mx2 = mx1; mx1 = mx[to];
		} else if (mx[to] >= mx2) mx2 = mx[to];
	}
	if (!ff) {
		topar[a] = 0;
	} else {
		for (int to : v[a]) {
			if (to == p || val[to] != 1) continue;
			topar[to] = max(topar[to], topar[a] + 1);
			int vl = (mx[to] == mx1 ? mx2 : mx1);
			if (vl == 0) continue;
			topar[to] = max(topar[to],vl + 1);
		}
	}
	for (int to : v[a]) {
		if (to == p) continue;
		dfs1(to,a);
	}
}
void dfs2(int a, int p) {
	if (val[a] == 1) {
		vector <int> ans;
		for (int to : v[a]) {
			if (to == p) continue;
			ans.pb(mx[to] + 1);
		}
		ans.pb(topar[a]);
		sort(ans.begin(),ans.end());
		if (ans.size() >= 2) {
			answ = max(answ,ans.back() + ans[ans.size() - 2] - 1);
		} else {
			if (ans.size() >= 1) answ = max(answ,ans.back());
		}
	}
	if(val[a] == 2) {
		vector <int> ans;
		for (int to : v[a]) {
			if (to == p) continue;
			ans.pb(mx[to]);
		}
		ans.pb(topar[p]);
		sort(ans.begin(),ans.end());
		if (ans.size() >= 2) {
			answ1 = max(answ1, ans.back() + ans[ans.size() - 2]);
		}
	}
	for (int to : v[a]) {
		if (to == p) continue;
		dfs2(to,a);
	}
}
main() {
    std::ios_base::sync_with_stdio(false),cin.tie(0),cout.tie(0);
    cin>>n;
    for (int i = 1; i <= n - 1;i++) {
    	int x,y;
    	cin>>x>>y;
    	v[x].pb(y);
    	v[y].pb(x);
	}
	int mn = 1e9;
	for (int i = 1; i <= n; i++) {
		cin>>val[i];
		mn = min(mn,val[i]);
	}
	dfs(1,0);
	answ = -1; answ1 = -1;
	dfs1(1,0);
	
	dfs2(1,0);
	if (answ == -1) {
	    cout<<mn<<"/"<<1<<"\n";
	    exit(0);
	}
	answ1++;
	if (2 * answ <= answ1) {
	    if (answ1 % 2 == 0) {
	        cout<<1<<"/"<<answ1/2<<"\n";
	    } else
	    cout<<2<<"/"<<answ1<<"\n";
	    exit(0);
	}
	cout<<1<<"/"<<answ<<"\n";
}

Compilation message (stderr)

mag.cpp:254:1: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
  254 | main() {
      | ^~~~

• Subtask 1: 12 / 12
• Subtask 2: 12 / 12
• Subtask 3: 0 / 12
• Subtask 4: 0 / 12
• Subtask 5: 0 / 12
• Subtask 6: 0 / 12
• Subtask 7: 0 / 12
• Subtask 8: 0 / 12
• Subtask 9: 0 / 12
• Subtask 10: 0 / 12