#include #include #include #include #include typedef int32_t i32; typedef int64_t i64; typedef struct directed_edge { int32_t vertex; int32_t next; } graph_edge; typedef struct directedGraph { graph_edge *edge; int32_t *start; int32_t pointer; int32_t vertex_num; int32_t edge_max_size; } graph; graph* new_graph (const int vertex_num) { graph *g = (graph *) calloc (1, sizeof (graph)); g->edge = (graph_edge *) calloc (1, sizeof (graph_edge)); g->start = (int32_t *) calloc (vertex_num, sizeof (int32_t)); g->pointer = 0; g->vertex_num = vertex_num; g->edge_max_size = 1; for (int32_t i = 0; i < vertex_num; ++i) { g->start[i] = -1; } return g; } void add_edge (graph *g, int32_t from, int32_t to) { if (g->pointer == g->edge_max_size) { g->edge_max_size *= 2; g->edge = (graph_edge *) realloc (g->edge, sizeof (graph_edge) * g->edge_max_size); } g->edge[g->pointer] = (graph_edge) {to, g->start[from]}; g->start[from] = g->pointer++; } typedef struct union_find { int32_t *parent; i32 *sum; int32_t size; } union_find; void init_union_find (union_find * const u) { for (int32_t i = 0; i < u->size; ++i){ u->parent[i] = -1; u->sum[i] = 0; } } union_find* new_union_find (const int32_t size) { union_find * const u = (union_find *) calloc (1, sizeof (union_find)); u->parent = (int32_t *) calloc (size, sizeof (int32_t)); u->sum = (i32 *) calloc (size, sizeof (i32)); u->size = size; init_union_find (u); return u; } int32_t root (union_find * const u, int32_t x) { while (u->parent[x] >= 0) { x = u->parent[x]; } return x; } int same (union_find * const u, const int32_t x, const int32_t y) { return root (u, x) == root (u, y); } int32_t get_size (union_find * const u, const int32_t x) { return - (u->parent[root (u, x)]); } void unite (union_find * const u, int32_t x, int32_t y) { x = root (u, x); y = root (u, y); if (x == y) return; if (u->parent[x] > u->parent[y]) { const int32_t swap = x; x = y; y = swap; } u->parent[x] += u->parent[y]; u->parent[y] = x; u->sum[y] -= u->sum[x]; } void add (union_find *u, i32 x, i32 v) { u->sum[root (u, x)] += v; } i32 get_sum (union_find *u, i32 x) { i32 ans = u->sum[x]; while (u->parent[x] >= 0) { x = u->parent[x]; ans += u->sum[x]; } return ans; } void run (void) { i32 n; scanf ("%" SCNi32, &n); i32 *r = (i32 *) calloc (n, sizeof (i32)); for (i32 i = 0; i < n; ++i) { scanf ("%" SCNi32, r + i); } graph *g = new_graph (n); for (i32 i = 1; i < n; ++i) { i32 a, b; scanf ("%" SCNi32 "%" SCNi32, &a, &b); a--; b--; add_edge (g, a, b); add_edge (g, b, a); } union_find *u = new_union_find (n); for (i32 i = 0; i < n; ++i) { add (u, i, 1); for (i32 p = g->start[i]; p != -1; p = g->edge[p].next) { i32 v = g->edge[p].vertex; if (v > i) continue; add (u, v, 1); unite (u, i, v); } } const i32 mod = 1000000007; i32 ans = 1; for (i32 i = 0; i < n; ++i) { i32 c = get_sum (u, i); ans = (i64) ans * (r[i] + c) % mod; } printf ("%" PRIi32 "\n", ans); } int main (void) { run(); return 0; }