#include <bits/stdc++.h>
#define loop(i,a,b) for(int i = (a); i < (b); i ++)
#define pb push_back
#define ins insert
#define pii pair<int,int>
#define ff first
#define ss second
#define BAE(x) x.begin(), x.end()
#define op(x) cerr << #x << " = " << x << endl;
#define opa(x) cerr << #x << " = " << x << ", ";
#define ops(x) cerr << x;
#define opse(x) cerr << x << endl;
#define spac cerr << ' ';
#define entr cerr << endl;
#define STL(x) cerr << #x << " : "; for(auto &qwe:x) cerr << qwe << ' '; cerr << endl;
#define ARR(x, nnn) cerr << #x << " : "; loop(qwe,0,nnn) cerr << x[qwe] << ' '; cerr << endl;
#define bye exit(0);
using namespace std;
mt19937 RNG(chrono::steady_clock::now().time_since_epoch().count());
inline int rng(int l, int r){ return uniform_int_distribution<int>(l, r)(RNG); }
ostream& operator<<(ostream& os, pii A){ os << "[" << A.ff << ", " << A.ss << "]"; }
const int mxn = (int)(2e5) + 10;
int val[mxn], dep[mxn];
bool vis[mxn];
vector<int> E[mxn];
int jump[mxn][18]; // [v, x] => from v, jump 2^x times
void dfs(int v, int par, int dis){
dep[v] = dis;
for(auto &i:E[v]){
if(i == par) continue;
dfs(i, v, dis + 1);
jump[i][0] = v;
}
}
void init_lca(int n){
jump[0][0] = 0;
dfs(0, -1, 0);
loop(j,1,18){
loop(i,0,n){
jump[i][j] = jump[(jump[i][j-1])][j-1];
}
}
}
inline int lca(int a, int b){
if(dep[a] > dep[b]) swap(a, b);
int diff = dep[b] - dep[a];
loop(i,0,18){
if((diff >> i) & 1) b = jump[b][i];
}
if(a == b) return b;
for(int i = 17; i >= 0; i--){
if(jump[a][i] != jump[b][i]){
a = jump[a][i];
b = jump[b][i];
}
}
a = jump[a][0];
b = jump[b][0];
return b;
}
int fa[mxn], sz[mxn], comp_mx[mxn];
int get_father(int v){
if(fa[fa[v]] == fa[v]) return fa[v];
return fa[v] = get_father(fa[v]);
}
inline void merg(int x, int y){
x = get_father(x);
y = get_father(y);
if(x == y) return;
if(sz[x] < sz[y]) swap(x, y);
sz[x] += sz[y];
comp_mx[x] = (val[comp_mx[x]] > val[comp_mx[y]]) ? comp_mx[x] : comp_mx[y];
fa[y] = x;
}
inline int get_comp_max(int v){
return comp_mx[get_father(v)];
}
int main(){
ios::sync_with_stdio(false); cin.tie(0);
int n; cin >> n;
loop(i,0,n) cin >> val[i];
loop(i,0,n-1){
int u, v;
cin >> u >> v;
u--; v--;
E[u].pb(v);
E[v].pb(u);
}
init_lca(n);
loop(i,0,n){
fa[i] = comp_mx[i] = i;
sz[i] = 1;
}
vector<pii> ord_sort;
loop(i,0,n){
ord_sort.pb({val[i], i});
}
sort(BAE(ord_sort));
vector<int> ord;
for(auto &i:ord_sort) ord.pb(i.ss);
long long ans = 0;
for(auto &i:ord){
vis[i] = true;
for(auto &j:E[i]){
if(vis[j]){
int son = get_comp_max(j);
ans += dep[i] + dep[son] - dep[lca(i, son)] * 2;
merg(i, j);
}
}
}
cout << ans << '\n';
}
/*
10
5 1 10 3 8 2 4 7 9 6
1 2
2 3
3 4
4 5
5 6
6 7
7 8
8 9
9 10
*/
Compilation message
Main.cpp: In function 'std::ostream& operator<<(std::ostream&, std::pair<int, int>)':
Main.cpp:21:84: warning: no return statement in function returning non-void [-Wreturn-type]
21 | ostream& operator<<(ostream& os, pii A){ os << "[" << A.ff << ", " << A.ss << "]"; }
| ^
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
2 ms |
12640 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
2 ms |
12640 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
2 ms |
12640 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
2 ms |
12640 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
2 ms |
12640 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
2 ms |
12632 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
2 ms |
12640 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
