Submission #713888

#	Time	Username	Problem	Language	Result	Execution time	Memory
713888		kaxzert	Race (IOI11_race)	C++17	0 / 100	8 ms	14420 KiB

race

#include<bits/stdc++.h>

using namespace std;

#define fto(i, a, b) for(int i = a; i <= b; ++i)
#define fdto(i, a, b) for(int i = a; i >= b; --i)
#define bugarr(a, i, j) cout << #a << "{" << i << "..." << j << "}:"; fto(k, i, j-1) cout << a[k] << ", "; cout << a[j] << endl;
#define ll long long
#define db double
#define ldb long double
#define ff first
#define ss second
#define pb push_back
#define mp make_pair
#define eb emplace_back
#define vt vector
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
#define trav(i, a) for(auto &i : a)
#define sz(a) (int)a.size()
#define pi(a, b) pair<a, b>
#define fast ios::sync_with_stdio(false); cin.tie(0)

void setIO(string s) {
    if (sz(s) != 0) {
        freopen((s+".inp").c_str(),"r",stdin);
       // freopen((s+".out").c_str(),"w",stdout);
    }
}

void setIOusaco(string s) {
    if (sz(s) != 0) {
        freopen((s+".in").c_str(),"r",stdin);
        freopen((s+".out").c_str(),"w",stdout);
    }
}

template<typename T, typename V>
bool ckmin(T &a, V b) {return (b < a)? a = b, true : false;}
template<typename T, typename V>
bool ckmax(T &a, V b) {return (b > a)? a = b, true : false;}

void print(int x) {cout << x;}
void print(long long x) {cout << x;}
void print(unsigned x) {cout << x;}
void print(unsigned long long x) {cout << x;}
void print(double x) {cout << fixed << x;}
void print(long double x) {cout << fixed << x;}
void print(char x) {cout << "'" << x << "'";}
void print(string x) {cout << '"' << x << '"';}
void print(bool x) {cout << (x ? "true" : "false");}

template<typename T, typename V>
void print(const pair<T, V> &x) {cout << '{'; print(x.ff); cout << ", "; print(x.ss); cout << '}';}
template<typename T>
void print(const T &x) {int f = 0; cout << '{'; for (auto &i: x) cout << (f++ ? ", " : ""), print(i); cout << "}";}
void _print() {cout << "]" << endl;}
template <typename T, typename... V>
void _print(T t, V... v) {print(t); if (sizeof...(v)) cout << ", "; _print(v...);}

#define bug(x...) cout << "[" << #x << "] = ["; _print(x)

const int maxN = 200007;
set<pair<int, int> > gr[maxN];
int len[maxN], depth[maxN], n, k;
vt<pair<int, int> > ke[maxN];
int ans = (int)1e9;

void dfs(int u, int val, int p = -1) {
	len[u] = val;
	trav(c, ke[u]) {
		int v = c.ff;
		int l = c.ss;
		if (v == p) continue;
		depth[v] = depth[u] + 1;
		dfs(v, val+l, u);
	}
}

void dfs2(int u, int p = -1) {
	trav(c, ke[u]) {
		int v = c.ff;
		int l = c.ss;
		if (v == p) continue;
		dfs2(v, u);
	
		gr[v].insert(mp(len[v], depth[v]));
		auto it = gr[v].lower_bound(mp(k + len[u], -1));
		if (it != gr[v].end() && (it->ff) == k + len[u]) {
			if (u == 6) {bug(gr[v]);}
				ans = min(ans, it->ss - depth[u]); 
		}

		if (sz(gr[u]) < sz(gr[v])) {
			swap(gr[u], gr[v]);
		}
		trav(o, gr[v]) {
			int need = k - o.ff + len[u]*2;
			auto it = gr[u].lower_bound(mp(need, -1));
			if (it != gr[u].end() && (it->ff) == need) {
				ans = min(ans, it->ss + o.ss - 2*depth[u]);
			}
		}
		trav(o, gr[v]) gr[u].insert(o);
	}
}

int best_path(int n_, int k_, int edges[][2], int weights[]){
	//setIO("race_ioi2011");
    //ios::sync_with_stdio(false); cin.tie(0);
    n = n_;
	k = k_;
	fto(i, 0, n-2) {
		int u = edges[i][0];
		int v = edges[i][1];
		int l = weights[i];
		ke[u].pb(mp(v, l));
		ke[v].pb(mp(u, l));
	}
	
	dfs(0, 0);
	dfs2(0);

	return (ans == (int)1e9 ? -1 : ans);
	}

Compilation message (stderr)

race.cpp: In function 'void dfs2(int, int)':
race.cpp:83:7: warning: unused variable 'l' [-Wunused-variable]
   83 |   int l = c.ss;
      |       ^
race.cpp: In function 'void setIO(std::string)':
race.cpp:26:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   26 |         freopen((s+".inp").c_str(),"r",stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
race.cpp: In function 'void setIOusaco(std::string)':
race.cpp:33:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   33 |         freopen((s+".in").c_str(),"r",stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
race.cpp:34:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   34 |         freopen((s+".out").c_str(),"w",stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 0 / 9
• Subtask 2: 0 / 12
• Subtask 3: 0 / 22
• Subtask 4: 0 / 57