//#pragma GCC optimize ("O3")
//#pragma GCC target ("sse4")
#include <bits/stdc++.h>
using namespace std;
template<class T> using min_heap = priority_queue<T, vector<T>, greater<T>>;
#define FOR(i, a, b) for (int i=a; i<(b); i++)
#define F0R(i, a) for (int i=0; i<(a); i++)
#define F0R1(i, a) for (int i=1; i<=(a); i++)
#define FORd(i, a, b) for (int i = (b)-1; i >= a; i--)
#define F0Rd(i, a) for (int i = (a)-1; i >= 0; i--)
#define trav(a, x) for (auto& a : x)
#define MIN(a, b) a = min(a, b)
#define MAX(a, b) a = max(a, b)
#define INF 1000000010
#define LL_INF 4500000000000000000LL
#define LSOne(S) (S & (-S))
#define EPS 1e-9
#define pA first
#define pB second
#define mp make_pair
#define mt make_tuple
#define pb push_back
#define eb emplace_back
#define PI acos(-1.0)
// #define MOD (int)(2e+9+11)
#define MOD (int)(1e+9+7)
#define SET(vec, val, size) for (int i = 0; i < size; i++) vec[i] = val;
#define SET2D(arr, val, dim1, dim2) F0R(i, dim1) F0R(j, dim2) arr[i][j] = val;
#define SET3D(arr, val, dim1, dim2, dim3) F0R(i, dim1) F0R(j, dim2) F0R(k, dim3) arr[i][j][k] = val;
#define SET4D(arr, val, dim1, dim2, dim3, dim4) F0R(i, dim1) F0R(j, dim2) F0R(k, dim3) F0R(l, dim4) arr[i][j][k][l] = val;
#define lb lower_bound
#define ub upper_bound
#define sz(x) (int)x.size()
#define beg(x) x.begin()
#define en(x) x.end()
#define all(x) beg(x), en(x)
#define resz resize
#define SORT(vec) sort(all(vec))
#define RSORT(vec) sort(vec.rbegin(),vec.rend())
typedef long long ll;
typedef long double ld;
typedef unsigned long long ull;
typedef pair<int, int> ii;
typedef pair<int, ii> iii;
typedef pair<ll, ll> pll;
typedef vector<int> vi;
typedef vector<ii> vii;
typedef vector<iii> viii;
typedef vector<ll> vl;
// @formatter:off
// Source: Benq (https://github.com/bqi343/USACO) [Modified]
namespace input {
template<class T> void re(complex<T>& x);
template<class T1, class T2> void re(pair<T1,T2>& p);
template<class T> void re(vector<T>& a);
template<class T, size_t SZ> void re(array<T,SZ>& a);
template<class T> void reA(T A[], int sz);
template<class T> void re(T& x) { cin >> x; }
void re(double& x) { string t; re(t); x = stod(t); }
void re(ld& x) { string t; re(t); x = stold(t); }
template<class Arg, class... Args> void re(Arg& first, Args&... rest) {
re(first); re(rest...);
}
template<class T1, class T2> void re(pair<T1,T2>& p) { re(p.pA,p.pB); }
template<class T> void re(vector<T>& a) { F0R(i,sz(a)) re(a[i]); }
template<class T, size_t SZ> void re(array<T,SZ>& a) { F0R(i,SZ) re(a[i]); }
template<class T> void reA(T A[], int sz) { F0R(i, sz) re(A[i]); }
void setupIO(const string &PROB = "") {
ios::sync_with_stdio(false);
cin.tie(nullptr);
if (PROB.length() != 0) {
ifstream infile(PROB + ".in");
if (infile.good()) {
freopen((PROB + ".in").c_str(), "r", stdin);
freopen((PROB + ".out").c_str(), "w", stdout);
}
}
}
}
using namespace input;
namespace output {
template<class T1, class T2> void prD(const pair<T1,T2>& x);
template<class T, size_t SZ> void prD(const array<T,SZ>& x);
template<class T> void prD(const vector<T>& x);
template<class T> void prD(const set<T>& x);
template<class T1, class T2> void prD(const map<T1,T2>& x);
template<class T1, class T2> void pr(const pair<T1,T2>& x);
template<class T, size_t SZ> void pr(const array<T,SZ>& x);
template<class T> void pr(const vector<T>& x);
template<class T> void pr(const set<T>& x);
template<class T1, class T2> void pr(const map<T1,T2>& x);
template<class T> void prD(const T& x) { cout << x; cout.flush(); }
template<class Arg, class... Args> void prD(const Arg& first, const Args&... rest) {
prD(first); prD(rest...);
}
template<class T1, class T2> void prD(const pair<T1,T2>& x) {
prD("{",x.pA,", ",x.pB,"}");
}
template<class T> void prDContain(const T& x) {
prD("{");
bool fst = 1; for (const auto& a: x) prD(!fst?", ":"",a), fst = 0; // const needed for vector<bool>
prD("}");
}
template<class T, size_t SZ> void prD(const array<T,SZ>& x) { prDContain(x); }
template<class T> void prD(const vector<T>& x) { prDContain(x); }
template<class T> void prD(const set<T>& x) { prDContain(x); }
template<class T1, class T2> void prD(const map<T1,T2>& x) { prDContain(x); }
void psD() { prD("\n"); }
template<class Arg> void psD(const Arg& first) {
prD(first); psD(); // no space at end of line
}
template<class Arg, class... Args> void psD(const Arg& first, const Args&... rest) {
prD(first," "); psD(rest...); // print w/ spaces
}
template<class T> void pr(const T& x) { cout << x; }
template<class Arg, class... Args> void pr(const Arg& first, const Args&... rest) {
pr(first); pr(rest...);
}
template<class T1, class T2> void pr(const pair<T1,T2>& x) {
pr(x.pA, " ", x.pB);
}
template<class T> void prContain(const T& x) {
bool fst = 1; for (const auto& a: x) pr(!fst?" ":"",a), fst = 0; // const needed for vector<bool>
}
template<class T, size_t SZ> void pr(const array<T,SZ>& x) { prContain(x); }
template<class T> void pr(const vector<T>& x) { prContain(x); }
template<class T> void pr(const set<T>& x) { prContain(x); }
template<class T1, class T2> void pr(const map<T1,T2>& x) { prContain(x); }
void ps() { pr("\n"); }
template<class Arg> void ps(const Arg& first) {
pr(first); ps(); // no space at end of line
}
template<class Arg, class... Args> void ps(const Arg& first, const Args&... rest) {
pr(first," "); ps(rest...); // print w/ spaces
}
}
using namespace output;
// @formatter:on
/* ============================ */
#define MAXN 100000
int n;
vector<pair<int, ll>> adj[MAXN];
vl A;
int nodeSz[MAXN];
bool marked[MAXN];
ll ans = 0;
vector<pair<ll, int>> costFromCentroid;
int costIdx[MAXN];
ll ft[MAXN+10];
void upd(int k, int v, int n) {
for (; k <= n; k += LSOne(k)) ft[k] += v;
}
ll qry(int k) {
ll sum = 0; for (; k; k -= LSOne(k)) sum += ft[k];
return sum;
}
int dfsSize(int u, int p) {
nodeSz[u] = 1;
trav(v, adj[u]) {
if (v.pA != p && !marked[v.pA]) {
nodeSz[u] += dfsSize(v.pA, u);
}
}
return nodeSz[u];
}
int getCentroid(int u, int p, int totSz) {
trav(v, adj[u]) {
if (v.pA == p || marked[v.pA]) continue;
if (nodeSz[v.pA] > totSz/2) return getCentroid(v.pA, u, totSz);
}
return u;
}
void dfsCostFromCentroid(int u, int p, ll cost, ll sum) {
costFromCentroid.pb({cost,u});
trav(v, adj[u]) {
if (marked[v.pA] || v.pA == p) continue;
dfsCostFromCentroid(v.pA, u, min(cost, sum + A[u] - v.pB), sum + A[u] - v.pB);
}
}
vl costsToCentroid;
void dfsCostToCentroid(int u, int p, ll cost, ll sum) {
if (cost >= 0) {
costsToCentroid.pb(sum);
}
trav(v, adj[u]) {
if (marked[v.pA] || v.pA == p) continue;
dfsCostToCentroid(v.pA, u, min(A[v.pA] - v.pB, cost + (A[v.pA] - v.pB)), sum + A[v.pA] - v.pB);
}
}
void solve(int node) {
dfsSize(node, node);
int centroid = getCentroid(node, node, nodeSz[node]);
marked[centroid] = true;
trav(v, adj[centroid]) {
if (marked[v.pA]) continue;
dfsCostFromCentroid(v.pA, centroid, A[centroid] - v.pB, A[centroid] - v.pB);
}
trav(x, costFromCentroid) if (x.pA >= 0) ans++;
sort(all(costFromCentroid));
vector<pair<ll, int>> allCostsFromCentroid = costFromCentroid;
int ftsz = sz(allCostsFromCentroid)+1;
SET(ft, 0, ftsz+1);
F0R(i, sz(costFromCentroid)) {
costIdx[costFromCentroid[i].pB] = i+1;
upd(i+1, 1, ftsz);
}
trav(v, adj[centroid]) {
if (marked[v.pA]) continue;
costFromCentroid.clear();
dfsCostFromCentroid(v.pA, centroid, A[centroid] - v.pB, A[centroid] - v.pB);
trav(x, costFromCentroid) upd(costIdx[x.pB], -1, ftsz); // remove
dfsCostToCentroid(v.pA, centroid, A[v.pA] - v.pB, A[v.pA] - v.pB);
trav(cost, costsToCentroid) {
auto it = lower_bound(all(allCostsFromCentroid), mp(-cost, -1));
if (it != allCostsFromCentroid.end()) ans += qry(ftsz) - qry(costIdx[it->pB] - 1);
if (cost >= 0) ans++; // Go to the centroid and stop
}
costsToCentroid.clear();
trav(x, costFromCentroid) upd(costIdx[x.pB], 1, ftsz); // add
}
costFromCentroid.clear();
trav(v, adj[centroid]) {
if (marked[v.pA]) continue;
solve(v.pA);
}
}
int main() {
setupIO();
re(n);
A.resz(n); re(A);
F0R(i, n-1) {
int a, b, w; re(a, b, w); --a; --b;
adj[a].pb({b, w});
adj[b].pb({a, w});
}
solve(0);
ps(ans);
return 0;
}
Compilation message
transport.cpp: In function 'void input::setupIO(const string&)':
transport.cpp:85:24: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
freopen((PROB + ".in").c_str(), "r", stdin);
~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
transport.cpp:86:24: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
freopen((PROB + ".out").c_str(), "w", stdout);
~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
11 ms |
3064 KB |
Output is correct |
| 2 |
Correct |
10 ms |
3320 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
13 ms |
3448 KB |
Output is correct |
| 2 |
Correct |
16 ms |
3704 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
142 ms |
10376 KB |
Output is correct |
| 2 |
Correct |
122 ms |
10660 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
201 ms |
13040 KB |
Output is correct |
| 2 |
Correct |
222 ms |
16232 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
288 ms |
16960 KB |
Output is correct |
| 2 |
Correct |
326 ms |
22608 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
105 ms |
6132 KB |
Output is correct |
| 2 |
Correct |
51 ms |
6128 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
97 ms |
8044 KB |
Output is correct |
| 2 |
Correct |
162 ms |
8928 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
239 ms |
9912 KB |
Output is correct |
| 2 |
Correct |
213 ms |
12068 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
338 ms |
12264 KB |
Output is correct |
| 2 |
Correct |
325 ms |
14404 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
507 ms |
15788 KB |
Output is correct |
| 2 |
Correct |
447 ms |
16740 KB |
Output is correct |
