HDU 4670 Cube number on a tree

#include <map>   #include <vector>   #include <cstdio>   #include <cstdlib>   #include <cstring>   #include <iostream>   using namespace std;  const int N = 5e4+10;  const int K = 32;  typedef long long LL;    struct edge_t {    int v, to;  };  vector<edge_t> E;  int L[N];  void init(int n) {    E.clear();    memset(L, -1, sizeof(int)*n);  }  void add_edge(int u, int v) {    edge_t t = {v, L[u]};    L[u] = E.size();    E.push_back(t);  }    int n, k;  LL w[N], p[K];    LL ll_split(LL x) {    LL rv = 0;    for (int i = 0; i < k; i++) {      LL o = 0;      for ( ; x%p[i] == 0; x/= p[i]) o++;      rv |= o%3<<(i<<1);    }    return rv;  }  LL ll_add(LL lhs, LL rhs) {    LL rv = 0;    for (int i = 0; i < k; i++) {      LL o = ((lhs>>(i<<1)&3)+(rhs>>(i<<1)&3))%3;      rv |= o<<(i<<1);    }    return rv;  }  LL ll_com(LL x) {    LL rv = 0;    for (int i = 0; i < k; i++) {      rv |= (3-(x>>(i<<1)&3))%3<<(i<<1);    }    return rv;  }  void ll_show(LL x) {    for (int i = 0; i < k; i++) {      printf("%lld ", x>>(i<<1)&3);    }  }    bool vis[N];  int size, s[N];  void get_size(int u) {    vis[u] = 1;    s[u] = 1;    for (int i = L[u]; ~i; i = E[i].to) {      int v = E[i].v;      if (vis[v]) continue;      get_size(v);      s[u] += s[v];    }    vis[u] = 0;  }  int core;  void find_core(int u) {    vis[u] = 1;    int flag = 1;    for (int i = L[u]; ~i; i = E[i].to) {      int v = E[i].v;      if (vis[v]) continue;      if (s[v] > size/2) flag = 0;      find_core(v);    }    if (flag && size-s[u] <= size/2) core = u;    vis[u] = 0;  }  vector<LL> dis;  void get_dis(int u, LL d) {    vis[u] = 1;    dis.push_back(ll_add(w[u], d));    for (int i = L[u]; ~i; i = E[i].to) {      int v = E[i].v;      if (vis[v]) continue;      get_dis(v, ll_add(w[u], d));    }    vis[u] = 0;  }  int dac(int u) {    get_size(u);    size = s[u];    if (size == 1) return !w[u];    find_core(u);    int rv = !w[u = core];    vis[u] = 1;    map<LL, int> m;    m[0]++;    for (int i = L[u]; ~i; i = E[i].to) {      int v = E[i].v;      if (vis[v]) continue;      dis.clear();      get_dis(v, 0);      for (int j = 0; j < dis.size(); j++) {        map<LL, int>::iterator it = m.find(ll_com(ll_add(dis[j], w[u])));        if (it != m.end()) rv += it->second;      }      for (int j = 0; j < dis.size(); j++) m[dis[j]]++;    }    for (int i = L[u]; ~i; i = E[i].to) {      int v = E[i].v;      if (vis[v]) continue;      rv += dac(v);    }    vis[u] = 0;    return rv;  }    int main() {    for ( ; ~scanf("%d", &n); ) {      init(n);      scanf("%d", &k);      for (int i = 0; i < k; i++) {        char b[32];        scanf("%s", b);        p[i] = atoll(b);      }      for (int i = 0; i < n; i++) {        char b[32];        scanf("%s", b);        w[i] = ll_split(atoll(b));      }      for (int i = 0; i < n-1; i++) {        int u, v;        scanf("%d%d", &u, &v);        u--, v--;        add_edge(u, v);        add_edge(v, u);      }      printf("%d\n", dac(0));    }    return 0;  }