Submission #724842

#	Time	Username	Problem	Language	Result	Execution time	Memory
724842		Chal1shkan	Race (IOI11_race)	C++14	21 / 100	3051 ms	153596 KiB

race

# include <bits/stdc++.h>
# include "race.h"
 
# define pb push_back
# define ff first
# define ss second
# define nl "\n"
# define sz(x) ((int)(x).size())
# define deb(x) cerr << #x  << " = " << x << endl; 
# define pll pair <ll, ll>
# define pii pair <int, int> 
 
typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
 
const ll maxn = 2e5 + 25;
const ll inf = 2e9 + 0;
const ll mod = 998244353;
const ll dx[] = {-1, 1, 0, 0};
const ll dy[] = {0, 0, -1, 1};
 
using namespace std;
 
int n, k, ans;
vector <pii> g[maxn];
int sz[maxn];
bool used[maxn];
map <ll, int> mn;
 
void dfs_calc (int v, int pa)
{
	sz[v] = 1;
	for (pii i : g[v])
	{
		int to = i.ff, w = i.ss;
		if (to == pa || used[to]) continue;
		dfs_calc(to, v);
		sz[v] += sz[to];
	}
}
 
int find_c (int v, int pa, int siz)
{
	for (pii i : g[v])
	{
		int to = i.ff, w = i.ss;
		if (to == pa || used[to]) continue;
		if (sz[to] + sz[to] > siz)
		{
			return find_c(to, v, siz);
		}
	}
	return v;
}
 
void dfs_add (int v, int pa, int d1, int d2)
{
	mn[d1] = min(mn[d1], d2);
	for (pii i : g[v])
	{
		int to = i.ff, w = i.ss;
		if (to == pa || used[to]) continue;
		dfs_add(to, v, d1 + w, d2 + 1);
	}
}
 
void dfs_del (int v, int pa, ll d1, int d2)
{
	mn[d1] = inf;
	for (pii i : g[v])
	{
		int to = i.ff, w = i.ss;
		if (to == pa || used[to]) continue;
		dfs_del(to, v, d1 + w, d2 + 1);
	}
}
 
void dfs_ans (int v, int pa, ll d1, int d2)
{
	if (d1 > k) return;
	ans = min(ans, d2 + mn[k - d1]);
	for (pii i : g[v])
	{
		int to = i.ff, w = i.ss;
		if (to == pa || used[to]) continue;
		dfs_ans(to, v, d1 + w, d2 + 1);
	}
}
 
void centroid (int v)
{
	dfs_calc(v, v);
	v = find_c(v, v, sz[v]);
	for (pii i : g[v])
	{
		int to = i.ff, w = i.ss;
		if (used[to]) continue;
		dfs_ans(to, v, w, 1);
		dfs_add(to, v, w, 1);
	}
	for (pii i : g[v])
	{
		int to = i.ff, w = i.ss;
		if (used[to]) continue;
		dfs_del(to, v, w, 1);
	}
	used[v] = 1;
	for (pii i : g[v])
	{
		int to = i.ff, w = i.ss;
		if (used[to]) continue;
		centroid(to);	
	}
}
 
int best_path(int N, int K, int H[][2], int L[])
{
  n = N, k = K, ans = inf;
  for(int i = 0; i < n - 1; ++i){
    g[H[i][0] + 1].pb({H[i][1] + 1, L[i]});
    g[H[i][1] + 1].pb({H[i][0] + 1, L[i]});
  }
  for (int i = 1; i <= k; ++i) mn[i] = inf; 
  centroid(1);
  return (ans == inf ? -1 : ans);
}

Compilation message (stderr)

race.cpp: In function 'void dfs_calc(int, int)':
race.cpp:36:18: warning: unused variable 'w' [-Wunused-variable]
   36 |   int to = i.ff, w = i.ss;
      |                  ^
race.cpp: In function 'int find_c(int, int, int)':
race.cpp:47:18: warning: unused variable 'w' [-Wunused-variable]
   47 |   int to = i.ff, w = i.ss;
      |                  ^
race.cpp: In function 'void centroid(int)':
race.cpp:111:18: warning: unused variable 'w' [-Wunused-variable]
  111 |   int to = i.ff, w = i.ss;
      |                  ^

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