#include <bits/stdc++.h>
#define fo(i, d, c) for (int i = d; i <= c; i++)
#define fod(i, c, d) for (int i = c; i >= d; i--)
#define maxn 1000010
#define N 1010
#define fi first
#define se second
#define pb emplace_back
#define en cout << "\n";
#define int long long
#define inf (int)1e18
#define pii pair<int, int>
#define vii vector<pii>
#define lb(x) x & -x
#define bit(i, j) ((i >> j) & 1)
#define offbit(i, j) (i ^ (1 << j))
#define onbit(i, j) (i | (1 << j))
#define vi vector<int>
template <typename T1, typename T2>
bool minimize(T1 &a, T2 b)
{
if (a > b)
{
a = b;
return true;
}
return false;
}
template <typename T1, typename T2>
bool maximize(T1 &a, T2 b)
{
if (a < b)
{
a = b;
return true;
}
return false;
}
using namespace std;
const int nsqrt = 450;
const int mod = 1e9 + 7;
struct BIT
{
int t[maxn];
void up(int x, int val)
{
x++;
for (; x; x -= lb(x))
t[x] += val;
}
int get(int x)
{
int ans = 0;
x++;
for( ; x < maxn ; x += lb(x))
ans += t[x];
return ans;
}
} t;
int n;
vii ke[maxn];
int a[maxn];
vi event;
int ans;
// centroid decomposition
bool is_remove[maxn];
int sz[maxn];
int dfs_size(int u, int parent = -1)
{
sz[u] = 1;
for (auto [v, w] : ke[u])
{
if (v == parent or is_remove[v])
continue;
sz[u] += dfs_size(v, u);
}
return sz[u];
}
int dfs_centroid(int u, int tree_size, int parent = 0)
{
for (auto [v, w] : ke[u])
{
if (v == parent or is_remove[v])
continue;
if (2 * sz[v] > tree_size)
return dfs_centroid(v, tree_size, u);
}
return u;
}
void up(int u, int par, int update, int gas, int minn)
{
// cout << u << ' ' << gas << ' ' << minn << "\n";
if (minn >= 0)
{
int lb = lower_bound(event.begin(), event.end(), gas) - event.begin() + 1;
t.up(lb, update);
}
for (auto [v, w] : ke[u])
{
if (v == par or is_remove[v])
continue;
up(v, u, update, gas + a[v] - w, min(minn + a[v] - w, a[v] - w));
}
}
void get(int u, int par, int gas, int minn)
{
// cout << u << ' ' << gas << ' ' << minn << "\n";
int lb = lower_bound(event.begin(), event.end(), -minn) - event.begin() + 1;
ans += t.get(lb);
for (auto [v, w] : ke[u])
{
if (v == par or is_remove[v])
continue;
get(v, u, gas + a[v] - w, min(minn, gas - w));
}
}
void dfs_dist(int u, int par, int centroid,int gas, int minn)
{
// cout << u << ' ' << gas << ' ' << minn << "xxx\n";
if (minn >= 0)
ans += (u != centroid),event.pb(gas);
for (auto [v, w] : ke[u])
{
if (v == par or is_remove[v])
continue;
dfs_dist(v, u,centroid, gas - w + a[v], min(minn + a[v] - w, a[v] - w));
}
}
void build_centroid(int u)
{
u = dfs_centroid(u, dfs_size(u));
is_remove[u] = 1;
// cout << u;en;
// do sth
dfs_dist(u, u,u, a[u], a[u]);
sort(event.begin(),event.end());
event.erase(unique(event.begin(),event.end()),event.end());
// if(u == 2)
// for(int it : event) cout << it << "\n";
up(u, u, 1, a[u], a[u]);
for (auto [v, w] : ke[u])
{
if (is_remove[v])
continue;
up(v, u, -1, a[u] - w + a[v],min(a[u] - w + a[v],a[v] - w));
get(v, u, a[v] - w, - w);
up(v, u, 1, a[u] - w + a[v],min(a[u] - w + a[v],a[v] - w));
}
up(u, u, -1, a[u], a[u]);
event.clear();
// cout << u << ' ' << ans;en;
for (auto [v, w] : ke[u])
{
if (is_remove[v])
continue;
build_centroid(v);
}
}
main()
{
#define name "TASK"
if (fopen(name ".inp", "r"))
{
freopen(name ".inp", "r", stdin);
freopen(name ".out", "w", stdout);
}
ios_base::sync_with_stdio(false);
cin.tie(NULL);
cin >> n;
fo(i, 1, n) cin >> a[i];
fo(i, 1, n - 1)
{
int u, v, w;
cin >> u >> v >> w;
ke[u].pb(v, w);
ke[v].pb(u, w);
}
build_centroid(1);
cout << ans;
}
Compilation message
transport.cpp:159:1: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
159 | main()
| ^~~~
transport.cpp: In function 'int main()':
transport.cpp:164:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
164 | freopen(name ".inp", "r", stdin);
| ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
transport.cpp:165:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
165 | freopen(name ".out", "w", stdout);
| ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
23 ms |
27412 KB |
Output is correct |
| 2 |
Correct |
11 ms |
27484 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
14 ms |
27740 KB |
Output is correct |
| 2 |
Correct |
12 ms |
27740 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
116 ms |
35528 KB |
Output is correct |
| 2 |
Correct |
66 ms |
34900 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
126 ms |
37772 KB |
Output is correct |
| 2 |
Correct |
113 ms |
38432 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
219 ms |
40740 KB |
Output is correct |
| 2 |
Correct |
190 ms |
42836 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
99 ms |
31576 KB |
Output is correct |
| 2 |
Correct |
38 ms |
31068 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
78 ms |
33152 KB |
Output is correct |
| 2 |
Correct |
111 ms |
32724 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
176 ms |
34544 KB |
Output is correct |
| 2 |
Correct |
128 ms |
34392 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
231 ms |
35808 KB |
Output is correct |
| 2 |
Correct |
238 ms |
35716 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
330 ms |
37968 KB |
Output is correct |
| 2 |
Correct |
247 ms |
36908 KB |
Output is correct |
