| # | Time | Username | Problem | Language | Result | Execution time | Memory |
|---|---|---|---|---|---|---|---|
| 770814 | nasam | Race (IOI11_race) | C++17 | 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>
#define ll long long
#define FOR(i,a,b) for (int i = (a), _b = (b); i <= _b; i++)
#define FOD(i,b,a) for (int i = (b), _a = (a); i >= _a; i--)
#define FORE(i, v) for (__typeof((v).begin()) i = (v).begin(); i != (v).end(); i++)
#define ALL(v) (v).begin(), (v).end()
#define BIT(x, i) (((x) >> (i)) & 1)
#define MASK(i) (1LL << (i))
#define CNTBIT(x) __builtin_popcount(x)
#define fi first
#define se second
#define pb push_back
#define eb emplace_back
#define left ___left
#define right ___right
#define pii pair<int, int>
#define DEBUG(n, a) FOR (i, 1, n) cout << a[i] << ' '; cout << endl;
#define lob lower_bound // >=
#define upb upper_bound // >
#define endl "\n"
#define NAME "main"
using namespace std;
template<class X, class Y> bool maximize(X &x, Y y){ if (x < y){ x = y; return true; } return false; }
template<class X, class Y> bool minimize(X &x, Y y){ if (x > y){ x = y; return true; } return false; }
#define gogobruhbruh ios_base::sync_with_stdio(false); cin.tie(nullptr); cout.tie(nullptr);
#define file(name) if (fopen (name".inp", "r")) { freopen (name".inp", "r", stdin); freopen (name".out", "w", stdout); }
int MOD = 1e9 + 7;
void add(int &a, int b){ if ((a += b) >= MOD) a -= MOD; }
int sub(int a, int b){ if ((a -= b) < 0) a += MOD; return a; }
int muti(int a, int b){ return (1LL * a * b) % MOD; }
int Pow(int x, int y){ int res = 1; for (; y; y >>= 1){ if (y & 1) res = muti(res, x); x = muti(x, x); } return res; }
const int K = 1e6 + 7;
const int MAX = 2e5 + 7;
const int INF = 1e9 + 7;
int num, target, res = INF;
vector<pii> edge[MAX], tmp;
int sz[MAX], dp[K], exist[K], type;
bool del[MAX];
struct CD {
void addEdge(int u, int v, int cost){
edge[u].pb({v, cost});
edge[v].pb({u, cost});
}
void dfs(int u, int pre){
sz[u] = 1;
for (auto[v, cost] : edge[u])
if (!del[v] && v != pre)
dfs(v, u),
sz[u] += sz[v];
}
int centroid(int u, int pre, int n){
for (auto[v, cost] : edge[u])
if (!del[v] && v != pre && sz[v] > n)
return centroid(v, u, n);
return u;
}
void dfs2(int u, int pre, int dep, int len){
if (dep > target)
return;
tmp.pb({dep, len});
if (exist[target - dep] == type)
minimize(res, len + dp[target - dep]);
for (auto[v, cost] : edge[u])
if (!del[v] && v != pre)
dfs2(v, u, dep + cost, len + 1);
}
void build(int u){
dfs(u, -1);
int root = centroid(u, -1, sz[u] >> 1);
exist[0] = ++type;
for (auto[v, cost] : edge[root]){
dfs2(v, root, cost, 1);
for (auto[dep, len] : tmp)
if (exist[dep] < type || (exist[dep] == type && dp[dep] > len))
exist[dep] = type,
dp[dep] = len;
tmp.clear();
}
del[root] = 1;
for (auto[v, cost] : edge[root])
if (!del[v])
build(v);
}
} cd;
void solve(){
cd.build(1);
if (res == INF)
res = -1;
printf("%d", res);
}
void read(){
scanf("%d %d", &num, &target);
FOR (i, 2, num){
static int u, v, cost;
scanf("%d %d %d", &u, &v, &cost);
cd.addEdge(++u, ++v, cost);
}
}
int main(){
gogobruhbruh;
file("main");
int test = 1;
// cin >> test;
while (test--)
read(),
solve();
}