//#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
//#pragma GCC optimize("unroll-loops")
#define _CRT_SECURE_NO_WARNINGS
#include <bits/stdc++.h>
using namespace std;
typedef pair <int, int> pii;
typedef pair <long long, long long> pll;
typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
#define endl "\n"
#define mt make_tuple
#define mp make_pair
template <typename T1, typename T2>
bool umax(T1 &a, const T2&b) { return a < b ? a = b, 1 : 0;}
template <typename T1, typename T2>
bool umin(T1 &a, const T2 &b) {return a > b ? a = b, 1 : 0;}
template <typename T>
T sqr(T a) {return a * a;}
mt19937 rng(20010709);
const int mod = 1000000007;
const int INF = 1000000001;
const ll INFLL = INF;
const int N = 100005;
const int M = 17;
struct Centroid {
int n, t;
vector <vector <pii>> e;
vector <int> locked, a, len;
vector <ll> globalUp, globalDown, localUp, localDown;
ll result;
Centroid() { }
void init(int N) {
n = N;
e.assign(n + 1, vector <pii>());
locked.assign(n + 1, 0);
a.assign(n + 1, 0);
len.assign(n + 1, 0);
result = 0;
}
int dfsLen(int v, int p = -1) {
len[v] = 1;
for (auto it : e[v]) {
if (!locked[it.first] && (it.first != p))
len[v] += dfsLen(it.first, v);
}
return len[v];
}
int findCentroid(int v) {
int p = -1, found = 1, fullLen = len[v];
while (found) {
found = 0;
for (auto it : e[v]) {
if (!locked[it.first] && (it.first != p) && (len[it.first] * 2 >= fullLen)) {
p = v;
v = it.first;
found = 1;
break;
}
}
}
return v;
}
void process(vector <ll> &up, vector <ll> &down, int d = 1) {
sort(up.begin(), up.end());
sort(down.begin(), down.end());
for (int i = 0, j = 0; i < down.size(); i++) {
while ((j < up.size()) && (up[j] < down[i]))
j++;
result += d * (1LL * up.size() - j);
}
}
void dfs(int v, int p, ll up, ll maxUp, ll down, ll maxDown) {
umax(maxDown, -down);
up += a[v];
down += a[v];
if (a[v] >= maxUp)
localUp.push_back(up);
localDown.push_back(maxDown);
for (auto it : e[v]) {
if (!locked[it.first] && (it.first != p))
dfs(it.first, v, up - it.second, it.second + max(0LL, maxUp - a[v]), down - it.second, maxDown);
}
}
void get(int v) {
dfsLen(v);
v = findCentroid(v);
t = a[v];
globalUp.clear();
globalDown.clear();
globalUp.push_back(0);
globalDown.push_back(-a[v]);
result--;
for (auto it : e[v]) {
if (!locked[it.first]) {
localUp.clear();
localDown.clear();
dfs(it.first, v, -it.second, it.second, (a[v] - it.second), 0);
process(localUp, localDown, -1);
globalUp.insert(globalUp.end(), localUp.begin(), localUp.end());
globalDown.insert(globalDown.end(), localDown.begin(), localDown.end());
}
}
process(globalUp, globalDown);
locked[v] = 1;
for (auto it : e[v]) {
if (!locked[it.first])
get(it.first);
}
}
ll solve() {
get(1);
return result;
}
};
int n;
Centroid c;
int main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
cin >> n;
c.init(n);
for (int i = 1; i <= n; i++)
cin >> c.a[i];
for (int i = 1; i < n; i++) {
int u, v, w;
cin >> u >> v >> w;
c.e[u].push_back({ v, w });
c.e[v].push_back({ u, w });
}
cout << c.solve() << endl;
return 0;
}
Compilation message
transport.cpp: In member function 'void Centroid::process(std::vector<long long int>&, std::vector<long long int>&, int)':
transport.cpp:84:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
for (int i = 0, j = 0; i < down.size(); i++) {
~~^~~~~~~~~~~~~
transport.cpp:85:14: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
while ((j < up.size()) && (up[j] < down[i]))
~~^~~~~~~~~~~
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
7 ms |
640 KB |
Output is correct |
| 2 |
Correct |
6 ms |
768 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
8 ms |
896 KB |
Output is correct |
| 2 |
Correct |
10 ms |
1024 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
73 ms |
6620 KB |
Output is correct |
| 2 |
Correct |
65 ms |
5760 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
100 ms |
8708 KB |
Output is correct |
| 2 |
Correct |
113 ms |
9688 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
147 ms |
11772 KB |
Output is correct |
| 2 |
Correct |
180 ms |
13996 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
78 ms |
3044 KB |
Output is correct |
| 2 |
Correct |
44 ms |
2656 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
68 ms |
4856 KB |
Output is correct |
| 2 |
Correct |
113 ms |
4128 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
218 ms |
5860 KB |
Output is correct |
| 2 |
Correct |
214 ms |
6268 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
264 ms |
7588 KB |
Output is correct |
| 2 |
Correct |
287 ms |
7980 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
365 ms |
9788 KB |
Output is correct |
| 2 |
Correct |
266 ms |
8728 KB |
Output is correct |
