| # | Time | Username | Problem | Language | Result | Execution time | Memory |
|---|---|---|---|---|---|---|---|
| 543835 | AJ00 | 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 <bits/stdc++.h>
#include "race.h"
using namespace std;
#define int long long
const int MAXN = 200001;
const int LOGN = 20;
vector<vector<pair<int,int>>> adj(MAXN);
int depth[MAXN],par[MAXN][LOGN],weight[MAXN][LOGN];
pair<int,int> lca(int x, int y){
int X = x, Y = y;
if (depth[X] < depth[Y]){
swap(x,y);
swap(X,Y);
}
int dh = depth[x]-depth[y];
int totw = 0;
for (int i = LOGN-1; i >= 0; i--){
if (dh&(1<<i)){
totw += weight[x][i];
x = par[x][i];
}
}
if (x == y){
return {totw, depth[X]-depth[Y]};
}
int lvl = 0;
for (int i = LOGN; i >= 0; i--){
if (par[x][i] != par[y][i]){
totw += weight[x][i];
totw += weight[y][i];
lvl += (1<<i);
x = par[x][i];
y = par[y][i];
}
}
totw += weight[x][0];
totw += weight[y][0];
lvl += 1;
lvl *= 2;
return {totw,lvl+depth[X]-depth[Y]};
}
void dfs(int x, int h = 0, int p= 0, int w = 0){
depth[x] = h;
par[x][0] = p;
weight[x][0] = w;
for (int i = 1; i < LOGN; i++){
par[x][i] = par[par[x][i-1]][i-1];
weight[x][i] = weight[x][i-1] + weight[par[x][i-1]][i-1];
}
for (auto ch: adj[x]){
int t = ch.first;
int wt = ch.second;
if (t != p){
dfs(t,h+1,x,wt);
}
}
}
int best_path(int N, int K, vector<vector<int>> H, vector<int> L[]){
for (int i = 0; i < N-1; i++){
adj[H[i][0]].push_back({H[i][1],L[i]});
adj[H[i][1]].push_back({H[i][0],L[i]});
}
dfs(0);
int ans = N;
for (int i = 0; i < N; i++){
for (int j = i+1; j < N; j++){
pair<int,int> l = lca(i,j);
if (l.first == K){
// cout << i << " " << j << " " << depth[i] << " " << depth[j] << "\n";
ans = min(ans,l.second);
}
}
}
ans -= (ans == N ? N+1 : 0);
return ans;
}