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  1. /* AUTHOR: TUAN ANH - BUI */
  2. // ~~ icebear ~~
  3. #include <bits/stdc++.h>
  4. using namespace std;
  5.  
  6. typedef long long ll;
  7. typedef pair<int, int> ii;
  8. typedef pair<int, ii> iii;
  9.  
  10. template<class X, class Y>
  11.     bool minimize(X &x, const Y &y) {
  12.         if (x > y) return x = y, true;
  13.         return false;
  14.     }
  15.  
  16. template<class X, class Y>
  17.     bool maximize(X &x, const Y &y) {
  18.         if (x < y) return x = y, true;
  19.         return false;
  20.     }
  21.  
  22. #define FOR(i,a,b) for(int i=(a); i<=(b); ++i)
  23. #define FORR(i,a,b) for(int i=(a); i>=(b); --i)
  24. #define REP(i, n) for(int i=0; i<(n); ++i)
  25. #define RED(i, n) for(int i=(n)-1; i>=0; --i)
  26. #define MASK(i) (1LL << (i))
  27. #define BIT(S, i) (((S) >> (i)) & 1)
  28. #define mp make_pair
  29. #define pb push_back
  30. #define fi first
  31. #define se second
  32. #define all(x) x.begin(), x.end()
  33. #define task "icebear"
  34. /*END OF TEMPLATE. ICEBEAR AND THE CAT WILL WIN TST26 */
  35.  
  36. const int MOD = 1e9 + 7;
  37. const int inf = (int)1e9 + 27092008;
  38. const ll INF  = (ll)1e18 + 27092008;
  39. const int N = 5e5 + 5;
  40. int n, q, p[N];
  41. vector<int> G[N];
  42. int par[N][20], cnt[N], sz[N], tin[N], ans[N], tout[N], tour[N], timer = 0, h[N];
  43. vector<ii> Q[N];
  44.  
  45. void dfs(int u) {
  46.     tin[u] = ++timer;
  47.     tour[timer] = u;
  48.     sz[u] = 1;
  49.     for(int v: G[u]) {
  50.         h[v] = h[u] + 1;
  51.         dfs(v);
  52.         sz[u] += sz[v];
  53.     }
  54.     tout[u] = timer;
  55. }
  56.  
  57. void sack(int u, bool keep = false) {
  58.     int hvy = 0;
  59.     for(int v : G[u]) if (sz[v] > sz[hvy])
  60.         hvy = v;
  61.  
  62.     for(int v : G[u]) if (v != hvy)
  63.         sack(v, false);
  64.  
  65.     if (hvy > 0) sack(hvy, true);
  66.  
  67.     for(int v : G[u]) if (v != hvy) {
  68.         FOR(i, tin[v], tout[v]) {
  69.             int x = tour[i];
  70.             cnt[h[x]]++;
  71.         }
  72.     }
  73.  
  74.     cnt[h[u]]++;
  75.     for(ii x : Q[u]) {
  76.         int k, i; tie(k, i) = x;
  77.         if (k + h[u] <= n) ans[i] = cnt[k + h[u]];
  78.     }
  79.  
  80.     if (keep == false) {
  81.         FOR(i, tin[u], tout[u]) {
  82.             int x = tour[i];
  83.             cnt[h[x]]--;
  84.         }
  85.     }
  86. }
  87.  
  88. int acs(int k, int v) {
  89.     RED(j, 20) if (BIT(k, j))
  90.         v = par[v][j];
  91.     return v;
  92. }
  93.  
  94. void init(void) {
  95.     cin >> n;
  96.     FOR(i, 1, n) {
  97.         cin >> p[i];
  98.         if (!p[i]) continue;
  99.         G[p[i]].pb(i);
  100.         par[i][0] = p[i];
  101.     }
  102.     cin >> q;
  103.     FOR(j, 1, 19) FOR(i, 1, n) par[i][j] = par[par[i][j - 1]][j - 1];
  104.     FOR(i, 1, q) {
  105.         int v, k;
  106.         cin >> v >> k;
  107.         int u = acs(k, v);
  108.         Q[u].pb(mp(k, i));
  109.     }
  110. }
  111.  
  112. void process(void) {
  113.     FOR(i, 1, n) if (p[i] == 0) {
  114.         dfs(i);
  115.         sack(i);
  116.     }
  117.     FOR(i, 1, q) cout << max(0, ans[i]-1) << ' ';
  118. }
  119.  
  120.  
  121. int main() {
  122.     ios_base::sync_with_stdio(0);
  123.     cin.tie(0); cout.tie(0);
  124.     if (fopen(task".inp", "r")) {
  125.         freopen(task".inp", "r", stdin);
  126.         freopen(task".out", "w", stdout);
  127.     }
  128.     int tc = 1;
  129. //    cin >> tc;
  130.     while(tc--) {
  131.         init();
  132.         process();
  133.     }
  134.     return 0;
  135. }
  136.  
  137.  
Success #stdin #stdout 0.01s 30440KB
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https://ideone.com/IQrTJm
language:
C++14 (gcc 8.3)
created:
8 hours ago
visibility:
public

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