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 | #include <bits/stdc++.h>
 using namespace std;
 
 typedef long long ll;
 const int N = 5e5 + 10, mod = 1e9 + 7;
 int root[N], tot = 0, num[N], len, a[N];
 struct Info {
 int sum, l, r;
 } info[N << 5];
 
 int getid(int x) {
 return lower_bound(num + 1, num + len + 1, x) - num;
 }
 
 void build(int &x, int l, int r) {
 x = ++tot;
 info[x].sum = 0;
 if (l == r) return;
 int mid = (l + r) / 2;
 build(info[x].l, l, mid);
 build(info[x].r, mid + 1, r);
 }
 
 void update(int pre, int &now, int l, int r, int q, int x) {
 now = ++tot;
 info[now] = info[pre];
 info[now].sum += x;
 info[now].sum %= mod;
 if (l == r) return;
 int mid = (l + r) / 2;
 if (mid >= q) update(info[pre].l, info[now].l, l, mid, q, x);
 else update(info[pre].r, info[now].r, mid + 1, r, q, x);
 }
 
 int query_sum(int pre, int now, int l, int r, int k) {
 if (l == r) return (info[now].sum - info[pre].sum + mod) % mod;
 int mid = (l + r) >> 1;
 if (k <= mid) return query_sum(info[pre].l, info[now].l, l, mid, k);
 else return ((info[info[now].l].sum - info[info[pre].l].sum + mod) % mod + query_sum(info[pre].r, info[now].r, mid + 1, r, k)) % mod;
 }
 
 vector<int> e[N];
 int lu[N], ru[N], id[N], pid, sz[N], ans, n, inv2 = 500000004, prex[N];
 
 void dfs(int u, int fa){
 lu[u] = ++pid;
 id[pid] = u;
 sz[u] = 1;
 for(int i : e[u]){
 if(i == fa) continue;
 dfs(i, u);
 sz[u] += sz[i];
 }
 ru[u] = pid;
 }
 
 template <typename T>
 struct Fenwick {
 const int n;
 vector<T> a;
 Fenwick(int n) : n(n), a(n + 1) {}
 void add(int x, T v) {
 while(x <= n){
 a[x] += v;
 a[x] %= mod;
 x += x & -x;
 }
 }
 T sum(int x) {
 T ans = 0;
 for (int i = x; i; i -= i & -i) {
 ans += a[i];
 ans %= mod;
 }
 return ans;
 }
 T rangeSum(int l, int r) {
 return (sum(r) - sum(l - 1) + mod) % mod;
 }
 };
 
 Fenwick<int> fsum(N), fcnt(N), fdp(N);
 
 void run(int u, int fa){
 int pos = getid(a[u]), cnt = fcnt.sum(pos);
 
 ll sum = 0, sum1 = ((1ll * cnt * n % mod - fdp.sum(pos)) + mod) % mod * sz[u] % mod;
 
 ll sum2 = prex[pos] - query_sum(root[lu[u] - 1], root[ru[u]], 1, len, pos);
 sum2 -= fsum.sum(pos);
 sum2 %= mod;
 if(sum2 < 0) sum2 += mod;
 sum2 = sum2 * sz[u] % mod;
 
 ll sum3 = 1ll * (sz[u] - 1) * (sz[u] - 2) % mod * inv2 % mod, sum4 = 0;
 sum3 = (sum3 + 1ll * (n - sz[u] + 1) * sz[u] % mod) % mod;
 for(int i : e[u]){
 if(i == fa) continue;
 sum4 += 1ll * (n - sz[i]) * query_sum(root[lu[i] - 1], root[ru[i]], 1, len, pos);
 sum4 %= mod;
 sum3 -= 1ll * (sz[i] - 1) * sz[i] % mod * inv2 % mod;
 sum3 %= mod;
 if(sum3 < 0) sum3 += mod;
 }
 
 
 sum = (sum1 + sum2 + sum3 + sum4) % mod;
 
 sum = sum * a[u] % mod;
 ans = (ans + sum) % mod;
 fcnt.add(pos, 1);
 fsum.add(pos, sz[u]);
 for(int i : e[u]){
 if(i == fa) continue;
 fdp.add(pos, sz[i]);
 run(i, u);
 fdp.add(pos, -sz[i]);
 }
 fsum.add(pos, -sz[u]);
 fcnt.add(pos, -1);
 }
 
 void solve() {
 cin >> n;
 for(int i = 1; i <= n; i++) cin >> a[i], num[i] = a[i];
 for(int i = 0, u, v; i < n - 1; i++){
 cin >> u >> v;
 e[u].push_back(v);
 e[v].push_back(u);
 }
 dfs(1, 0);
 sort(num + 1, num + 1 + n);
 len = unique(num + 1, num + 1 + n) - num - 1;
 build(root[0], 1, len);
 for(int i = 1; i <= pid; i++){
 int p = getid(a[id[i]]);
 update(root[i - 1], root[i], 1, len, p, sz[id[i]]);
 prex[p] = sz[id[i]];
 }
 for(int i = 1; i <= n; i++){
 prex[i] += prex[i - 1];
 prex[i] %= mod;
 }
 run(1, 0);
 cout << ans;
 }
 
 int main() {
 int T = 1;
 ios::sync_with_stdio(false);
 cin.tie(nullptr);
 
 while (T--) solve();
 return 0;
 }
 
 |