| # | Time | Username | Problem | Language | Result | Execution time | Memory |
|---|---|---|---|---|---|---|---|
| 237857 | T0p_ | Race (IOI11_race) | C++14 | 0 ms | 0 KiB |
This submission is migrated from previous version of oj.uz, which used different machine for grading. This submission may have different result if resubmitted.
#include "race.h"
#include <bits/stdc++.h>
using namespace std;
#define pb push_back
struct EDGE
{
int node, weight;
};
bool visit[200002];
int ans = 1e9;
int lv[200002], jmp[2][20][200002], sz[200002];
vector<int> gc[200002];
vector<EDGE> g[200002];
map<int, int> mp[200002];
void dfs(int u, int l)
{
lv[u] = l;
for(auto x : g[u])
{
if(lv[x.node]) continue ;
dfs(x.node, l+1);
jmp[0][0][x.node] = u;
jmp[1][0][x.node] = x.weight;
}
}
int get_sz(int u, int p)
{
sz[u] = 1;
for(auto x : g[u])
{
if(visit[x.node] || x.node == p) continue ;
sz[u] += get_sz(x.node, u);
}
return sz[u];
}
int get_centroid(int u, int p, int n)
{
bool ch = (n - sz[u] <= n/2) ? true : false;
int nn = 0, nf = 0;
for(auto x : g[u])
{
if(visit[x.node] || x.node == p) continue ;
if(sz[x.node] > n/2)
{
ch = false;
if(sz[x.node] > nf)
{
nn = x.node;
nf = sz[x.node];
}
}
}
return (ch) ? u : get_centroid(nn, u, n);
}
int build(int u, int p)
{
int c = get_centroid(u, p, get_sz(u, p));
visit[c] = true;
for(auto x : g[c])
{
if(visit[x.node]) continue ;
gc[c].pb(build(x.node, c));
}
return c;
}
pair<int, int> finddis(int u, int v)
{
int r1 = 0, r2 = 0;
if(lv[u] < lv[v]) swap(u, v);
for(int i=19 ; i>=0 ; i--)
if(lv[jmp[0][i][u]] >= lv[v])
{
r1 += (1<<i);
r2 += jmp[1][i][u];
u = jmp[0][i][u];
}
if(u == v) return {r1, r2};
for(int i=19 ; i>=0 ; i--)
if(jmp[0][i][u] != jmp[0][i][v])
{
r1 += (1<<(i+1));
r2 += jmp[1][i][u] + jmp[1][i][v];
u = jmp[0][i][u], v = jmp[0][i][v];
}
return {r1+2, r2+jmp[1][0][u] + jmp[1][0][v]};
}
void solve(int u)
{
for(auto x : gc[u])
solve(x);
for(auto x : gc[u])
{
pair<int, int> dis = finddis(u, x);
for(auto y : mp[x])
{
int a = y.first + dis.second;
int b = _K - a;
if(b <= 0) continue ;
if(mp[u].count(b)) ans = min(ans, mp[u][b] + y.second + dis.first);
}
for(auto y : mp[x])
{
int a = y.first + dis.second;
if(a > _K) continue ;
else if(a == _K) ans = min(ans, y.second + dis.first);
else if(mp[u].count(a)) mp[u][a] = min(mp[u][a], y.second + dis.first);
else mp[u][a] = y.second + dis.first;
}
}
mp[u][0] = 0;
}
int best_path(int N, int K, int H[][2], int L[])
{
int _K = K;
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]});
}
dfs(1, 1);
for(int i=1 ; i<20 ; i++)
for(int j=1 ; j<=N ; j++)
{
jmp[0][i][j] = jmp[0][i-1][jmp[0][i-1][j]];
jmp[1][i][j] = jmp[1][i-1][j] + jmp[1][i-1][jmp[0][i-1][j]];
}
solve(build(1, 0));
return (ans == 1e9) ? -1 : ans;
}