#include <bits/stdc++.h>
using namespace std;
void per() { cerr << endl; }
template <typename Head, typename... Tail>
void per(Head H, Tail... T) {
  cerr << H << ' ';
  per(T...);
}
template <class T>
bool uin(T& a, T b) {
  return a > b ? (a = b, true) : false;
}
template <class T>
bool uax(T& a, T b) {
  return a < b ? (a = b, true) : false;
}
template <class U, class V>
ostream& operator<<(ostream& out, const pair<U, V>& a) {
  return out << "(" << a.first << ", " << a.second << ")";
}
template <class U, class V>
istream& operator>>(istream& in, pair<U, V>& a) {
  return in >> a.first >> a.second;
}
template <typename W,
          typename T = typename enable_if<!is_same<W, string>::value,
                                          typename W::value_type>::type>
ostream& operator<<(ostream& out, const W& v) {
  out << "{ ";
  for (const auto& first : v) out << first << ", ";
  return out << '}';
}
template <class T>
void readArr(T from, T to) {
  for (auto i = from; i != to; ++i) cin >> *i;
}
mt19937 mrand(1337);
unsigned int myRand32() { return mrand() & (unsigned int)(-1); }
unsigned long long myRand64() {
  return ((unsigned long long)myRand32() << 32) ^ myRand32();
}
const int mod = 1000000007;
void add(int& a, int b) {
  a += b;
  if (a >= mod) a -= mod;
  if (a < 0) a += mod;
}
void dec(int& a, int b) {
  a -= b;
  if (a < 0) a += mod;
}
int mult(int a, int b) { return a * (long long)b % mod; }
int bp(int a, int b) {
  int res = 1;
  while (b > 0) {
    if (b & 1) res = mult(res, a);
    a = mult(a, a);
    b >>= 1;
  }
  return res;
}
int n, k;
vector<pair<int, int> > g[200007];
int a[200007];
const int MAXN = 2e5 + 7;
const size_t MAX_BIT = 18;
const size_t MAX_SIZE = 1 << MAX_BIT;
struct FenwickTree1 {
  int t[MAX_SIZE];
  int get(int v) {
    int res = 0;
    for (; v >= 0; v = (v & (v + 1)) - 1) {
      add(res, t[v]);
    }
    return res;
  }
  int get(int vl, int vr) {
    if (vl > vr) return 0;
    int res = get(vr);
    if (vl > 0) {
      dec(res, get(vl - 1));
    }
    return res;
  }
  void up(int v, int val) {
    for (; v < MAX_SIZE; v = v | (v + 1)) {
      add(t[v], val);
    }
  }
} F[2], G[2];
int RES = 0;
class CentroidDecomposition {
 public:
  int n;
  int w[MAXN];
  int del[MAXN];
  void CalcW(int v, int p = -1) {
    w[v] = 1;
    for (auto [to, _] : g[v])
      if (to != p && !del[to]) {
        CalcW(to, v);
        w[v] += w[to];
      }
  }
  int FindCentroid(int v, int total_w, int p = -1) {
    for (auto [to, _] : g[v])
      if (to != p && !del[to] && 2 * w[to] > total_w) {
        return FindCentroid(to, total_w, v);
      }
    return v;
  }
  void col(int v, int p, int first, int last, int co, int zn, int sum) {
    add(sum, a[v]);
    F[first].up(co, zn * sum);
    G[first].up(co, zn);
    for (auto [to, be] : g[v])
      if (to != p && !del[to]) {
        col(to, v, first, be, co + (be != last), zn, sum);
      }
  }
  void go(int v, int p, int first, int last, int co, int sum) {
    if (co > k) return;
    add(sum, a[v]);
    add(RES, F[first].get(0, k - co));
    add(RES, F[first ^ 1].get(0, k - co - 1));
    add(RES, mult(sum, G[first].get(0, k - co)));
    add(RES, mult(sum, G[first ^ 1].get(0, k - co - 1)));
    for (auto [to, be] : g[v])
      if (to != p && !del[to]) {
        go(to, v, first, be, co + (be != last), sum);
      }
  }
  int Build(int v) {
    CalcW(v);
    int c = FindCentroid(v, w[v]);
    for (auto [to, be] : g[c])
      if (!del[to]) {
        col(to, c, be, be, 0, 1, 0);
      }
    add(RES, a[c]);
    add(RES, F[0].get(0, k));
    add(RES, F[1].get(0, k));
    add(RES, mult(a[c], G[0].get(0, k)));
    add(RES, mult(a[c], G[1].get(0, k)));
    for (auto [to, be] : g[c])
      if (!del[to]) {
        col(to, c, be, be, 0, -1, 0);
        go(to, c, be, be, 0, a[c]);
      }
    del[c] = 1;
    for (auto [to, _] : g[c])
      if (!del[to]) {
        Build(to);
      }
    return c;
  }
} KEK;
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cin >> n >> k;
  readArr(a, a + n);
  for (int i = 0; i < n - 1; ++i) {
    int w1, w2, w3;
    cin >> w1 >> w2 >> w3;
    --w1;
    --w2;
    g[w1].push_back(make_pair(w2, w3));
    g[w2].push_back(make_pair(w1, w3));
  }
  KEK.Build(0);
  cout << RES;
}
