boj.11812.cc

#include <bits/stdc++.h>

using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<ll, ll> pll;
typedef pair<ull, ull> pull;
typedef const ll cll;
typedef queue<ll> qll;
typedef queue<pll> qpll;
typedef priority_queue<ll> pqll;
typedef priority_queue<pll> pqpll;
typedef vector<ll> vll;
typedef vector<pll> vpll;
typedef vector<vll> vvll;
typedef vector<vpll> vvpll;
#define FOR1(a, A) for (ll a = 0; a < A; ++a)
#define FOR2(a, b, A, B)                                                       \
  for (ll a = 0; a < A; ++a)                                                   \
    for (ll b = 0; b < B; ++b)

cll N = 1e15, K = 1e3, Q = 1e5;
ll n, k, q;
map<pll, ll> answers;

pll findDepth(ll x) {
  ll d = 0;
  if (k == 1) {
    return {x - 1, 0};
  }
  for (ll _d = 1; x > _d; _d *= k) {
    x -= _d, ++d;
  }

  return {d, --x};
}

int main(void) {
  ios::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);

  cin >> n >> k >> q;
  for (ll x, y, i = 0; i < q; ++i) {
    cin >> x >> y;
    pll infoX = findDepth(x), infoY = findDepth(y);
    ll depthX = infoX.first, depthY = infoY.first,
       minDepth = min(depthX, depthY);
    ll widthX = infoX.second, widthY = infoY.second;
    ll st = 0, en = minDepth, ans;
    while (st <= en) {
      ll mid = (st + en) / 2, _widthX, _widthY;

      _widthX = widthX / pow(k, depthX - mid);
      _widthY = widthY / pow(k, depthY - mid);

      if (_widthX == _widthY) {
        ans = depthX - mid + depthY - mid;
        st = mid + 1;
      } else {
        en = mid - 1;
      }
    }

    cout << ans << "\n";
  }

  return 0;
}