This submission is migrated from previous version of oj.uz, which used different machine for grading. This submission may have different result if resubmitted.
/*
"care a facut teste cu Lattice reduction attack e ciudat"
"linistiti va putin"
- 2023 -
*/
#include<bits/stdc++.h>
#include "race.h"
#define debug(x) cerr << #x << " " << x << "\n"
#define debugs(x) cerr << #x << " " << x << " "
#pragma GCC optimize("Ofast")
#define int long long
using namespace std;
struct edge
{
int to;
int cost;
};
int n,k;
int ans;
bool blocked[200001];
int sz[200001];
int h[200001][2];
int l[200001];
vector<edge> nodes[200001];
int f[1000001];
void recalc(int node, int parent)
{
sz[node]=1;
for (auto x : nodes[node])
{
if (x.to!=parent && !blocked[x.to])
{
recalc(x.to,node);
sz[node]+=sz[x.to];
}
}
}
int find_centroid(int compsize, int node, int parent)
{
for (auto x : nodes[node])
{
if (x.to!=parent && !blocked[x.to] && sz[x.to]>compsize/2)
return find_centroid(compsize,x.to,node);
}
return node;
}
void dfs(int node, int parent, int cost, int len)
{
if (k<cost)
return;
ans=min(ans,len+f[k-cost]);
for (auto x : nodes[node])
{
if (x.to!=parent && !blocked[x.to])
dfs(x.to,node,cost+x.cost,len+1);
}
}
void update(int node, int parent, int cost, int len)
{
f[cost]=min(f[cost],len);
for (auto x : nodes[node])
{
if (x.to!=parent && !blocked[x.to])
update(x.to,node,cost+x.cost,len+1);
}
}
void rem(int node, int parent, int cost)
{
f[cost]=n+1;
for (auto x : nodes[node])
{
if (x.to!=parent && !blocked[x.to])
rem(x.to,node,cost+x.cost);
}
}
void solve(int node)
{
int c,i;
recalc(node,-1);
c=find_centroid(sz[node],node,-1);
blocked[c]=1;
f[0]=0;
for (auto x : nodes[c])
{
if (!blocked[x.to])
{
dfs(x.to,c,x.cost,1);
update(x.to,c,x.cost,1);
}
}
for (auto x : nodes[c])
{
if (!blocked[x.to])
{
rem(x.to,c,x.cost);
}
}
for (auto x : nodes[c])
{
if (!blocked[x.to])
{
solve(x.to);
}
}
}
signed best_path(signed N, signed K, signed H[][2], signed L[])
{
int i,j,c,x,y;
n=N;
k=K;
for (i=0;i<=k;i++)
f[i]=n+1;
for (i=0; i<n; i++)
{
x=H[i][0];
y=H[i][1];
x++;
y++;
c=L[i];
nodes[x].push_back({y,c});
nodes[y].push_back({x,c});
}
ans=n+1;
solve(1);
if (ans!=n+1)
return ans;
else
return -1;
}
Compilation message (stderr)
race.cpp: In function 'void solve(long long int)':
race.cpp:87:11: warning: unused variable 'i' [-Wunused-variable]
87 | int c,i;
| ^
race.cpp: In function 'int best_path(int, int, int (*)[2], int*)':
race.cpp:118:11: warning: unused variable 'j' [-Wunused-variable]
118 | int i,j,c,x,y;
| ^
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