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Merge pull request #4987 from Sosuke23/fix
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update Baltic Editor
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@SansPapyrus683
SansPapyrus683 authored Jan 1, 2025
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359 changes: 85 additions & 274 deletions solutions/platinum/baltic-15-editor.mdx
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Expand Up @@ -7,7 +7,7 @@ author: Benjamin Qi

[Official Analysis](https://boi.cses.fi/files/boi2015_solutions.zip)

**Time Complexity:** $\mathcal O(N \log N)$.
## Explanation

Let `lev[x]=max(0,-a[x])`.

Expand Down Expand Up @@ -38,292 +38,103 @@ So the solution is to maintain the active path for every `i`. If there exists an
operation with level 0 on the active path for `i`, then its state is the answer
for `i`; otherwise, the answer for `i` is 0.

```cpp
#include <bits/stdc++.h>
using namespace std;

using ll = long long;
using ld = long double;
using db = double;
using str = string; // yay python!

using pi = pair<int, int>;
using pl = pair<ll, ll>;
using pd = pair<db, db>;

using vi = vector<int>;
using vb = vector<bool>;
using vl = vector<ll>;
using vd = vector<db>;
using vs = vector<str>;
using vpi = vector<pi>;
using vpl = vector<pl>;
using vpd = vector<pd>;

#define tcT template <class T
#define tcTU tcT, class U
// ^ lol this makes everything look weird but I'll try it
tcT > using V = vector<T>;
tcT, size_t SZ > using AR = array<T, SZ>;
tcT > using PR = pair<T, T>;

// pairs
#define mp make_pair
#define f first
#define s second

// vectors
// oops size(x), rbegin(x), rend(x) need C++17
#define sz(x) int((x).size())
#define bg(x) begin(x)
#define all(x) bg(x), end(x)
#define rall(x) x.rbegin(), x.rend()
#define sor(x) sort(all(x))
#define rsz resize
#define ins insert
#define ft front()
#define bk back()
#define pb push_back
#define eb emplace_back
#define pf push_front

#define lb lower_bound
#define ub upper_bound
tcT > int lwb(V<T> &a, const T &b) { return int(lb(all(a), b) - bg(a)); }

// loops
#define FOR(i, a, b) for (int i = (a); i < (b); ++i)
#define F0R(i, a) FOR(i, 0, a)
#define ROF(i, a, b) for (int i = (b) - 1; i >= (a); --i)
#define R0F(i, a) ROF(i, 0, a)
#define trav(a, x) for (auto &a : x)

const int MOD = 1e9 + 7; // 998244353;
const int MX = 2e5 + 5;
const ll INF = 1e18; // not too close to LLONG_MAX
const ld PI = acos((ld)-1);
const int dx[4] = {1, 0, -1, 0}, dy[4] = {0, 1, 0, -1}; // for every grid problem!!
mt19937 rng((uint32_t)chrono::steady_clock::now().time_since_epoch().count());
template <class T> using pqg = priority_queue<T, vector<T>, greater<T>>;

// bitwise ops
// also see https://gcc.gnu.org/onlinedocs/gcc/Other-Builtins.html
constexpr int pct(int x) { return __builtin_popcount(x); } // # of bits set
constexpr int bits(int x) { // assert(x >= 0); // make C++11 compatible until
// USACO updates ...
return x == 0 ? 0 : 31 - __builtin_clz(x);
} // floor(log2(x))
constexpr int p2(int x) { return 1 << x; }
constexpr int msk2(int x) { return p2(x) - 1; }

ll cdiv(ll a, ll b) {
return a / b + ((a ^ b) > 0 && a % b);
} // divide a by b rounded up
ll fdiv(ll a, ll b) {
return a / b - ((a ^ b) < 0 && a % b);
} // divide a by b rounded down

tcT > bool ckmin(T &a, const T &b) { return b < a ? a = b, 1 : 0; } // set a = min(a,b)
tcT > bool ckmax(T &a, const T &b) { return a < b ? a = b, 1 : 0; }

tcTU > T fstTrue(T lo, T hi, U f) {
hi++;
assert(lo <= hi); // assuming f is increasing
while (lo < hi) { // find first index such that f is true
T mid = lo + (hi - lo) / 2;
f(mid) ? hi = mid : lo = mid + 1;
}
return lo;
}
tcTU > T lstTrue(T lo, T hi, U f) {
lo--;
assert(lo <= hi); // assuming f is decreasing
while (lo < hi) { // find first index such that f is true
T mid = lo + (hi - lo + 1) / 2;
f(mid) ? lo = mid : hi = mid - 1;
}
return lo;
}
tcT > void remDup(vector<T> &v) { // sort and remove duplicates
sort(all(v));
v.erase(unique(all(v)), end(v));
}
tcTU > void erase(T &t, const U &u) { // don't erase
auto it = t.find(u);
assert(it != end(t));
t.erase(it);
} // element that doesn't exist from (multi)set

// INPUT
#define tcTUU tcT, class... U
tcT > void re(complex<T> &c);
tcTU > void re(pair<T, U> &p);
tcT > void re(V<T> &v);
tcT, size_t SZ > void re(AR<T, SZ> &a);

tcT > void re(T &x) { cin >> x; }
void re(db &d) {
str t;
re(t);
d = stod(t);
}
void re(ld &d) {
str t;
re(t);
d = stold(t);
}
tcTUU > void re(T &t, U &...u) {
re(t);
re(u...);
}

tcT > void re(complex<T> &c) {
T a, b;
re(a, b);
c = {a, b};
}
tcTU > void re(pair<T, U> &p) { re(p.f, p.s); }
tcT > void re(V<T> &x) { trav(a, x) re(a); }
tcT, size_t SZ > void re(AR<T, SZ> &x) { trav(a, x) re(a); }
tcT > void rv(int n, V<T> &x) {
x.rsz(n);
re(x);
}
## Implementation

// TO_STRING
#define ts to_string
str ts(char c) { return str(1, c); }
str ts(const char *s) { return (str)s; }
str ts(str s) { return s; }
str ts(bool b) {
#ifdef LOCAL
return b ? "true" : "false";
#else
return ts((int)b);
#endif
}
tcT > str ts(complex<T> c) {
stringstream ss;
ss << c;
return ss.str();
}
str ts(V<bool> v) {
str res = "{";
F0R(i, sz(v)) res += char('0' + v[i]);
res += "}";
return res;
}
template <size_t SZ> str ts(bitset<SZ> b) {
str res = "";
F0R(i, SZ) res += char('0' + b[i]);
return res;
}
tcTU > str ts(pair<T, U> p);
tcT > str ts(T v) { // containers with begin(), end()
#ifdef LOCAL
bool fst = 1;
str res = "{";
for (const auto &x : v) {
if (!fst) res += ", ";
fst = 0;
res += ts(x);
}
res += "}";
return res;
#else
bool fst = 1;
str res = "";
for (const auto &x : v) {
if (!fst) res += " ";
fst = 0;
res += ts(x);
}
return res;
**Time Complexity:** $\mathcal O(N \log N)$.

#endif
}
tcTU > str ts(pair<T, U> p) {
#ifdef LOCAL
return "(" + ts(p.f) + ", " + ts(p.s) + ")";
#else
return ts(p.f) + " " + ts(p.s);
#endif
}
<LanguageSection>
<CPPSection>

// OUTPUT
tcT > void pr(T x) { cout << ts(x); }
tcTUU > void pr(const T &t, const U &...u) {
pr(t);
pr(u...);
}
void ps() { pr("\n"); } // print w/ spaces
tcTUU > void ps(const T &t, const U &...u) {
pr(t);
if (sizeof...(u)) pr(" ");
ps(u...);
}
```cpp
#include <cassert>
#include <iostream>

// DEBUG
void DBG() { cerr << "]" << endl; }
tcTUU > void DBG(const T &t, const U &...u) {
cerr << ts(t);
if (sizeof...(u)) cerr << ", ";
DBG(u...);
}
#ifdef LOCAL // compile with -DLOCAL, chk -> fake assert
#define dbg(...) \
cerr << "Line(" << __LINE__ << ") -> [" << #__VA_ARGS__ << "]: [", DBG(__VA_ARGS__)
#define chk(...) \
if (!(__VA_ARGS__)) \
cerr << "Line(" << __LINE__ << ") -> function(" << __FUNCTION__ \
<< ") -> CHK FAILED: (" << #__VA_ARGS__ << ")" << "\n", \
exit(0);
#else
#define dbg(...) 0
#define chk(...) 0
#endif

void setPrec() { cout << fixed << setprecision(15); }
void unsyncIO() { cin.tie(0)->sync_with_stdio(0); }
// FILE I/O
void setIn(str s) { freopen(s.c_str(), "r", stdin); }
void setOut(str s) { freopen(s.c_str(), "w", stdout); }
void setIO(str s = "") {
unsyncIO();
setPrec();
// cin.exceptions(cin.failbit);
// throws exception when do smth illegal
// ex. try to read letter into int
if (sz(s)) setIn(s + ".in"), setOut(s + ".out"); // for USACO
}
const int MAX_N = 3e5 + 1;
const int MAX_D = 19; // ceil(log2(3*(10^5)))

int state[MX], par[MX][19], lev[MX];
int state[MAX_N], par[MAX_N][MAX_D], lev[MAX_N];

int getPar(int x,
int maxLev) { // get last op on active path of x with lev <= maxLev
if (lev[x] <= maxLev) return x;
R0F(i, 19) if (lev[par[x][i]] > maxLev) x = par[x][i];
/** get last op on active path of x with lev <= max_lev */
int get_par(int x, int max_lev) {
if (lev[x] <= max_lev) { return x; }
for (int i = MAX_D - 1; i >= 0; i--) {
if (lev[par[x][i]] > max_lev) { x = par[x][i]; }
}
return par[x][0];
}

int main() {
setIO();
int n;
re(n);
FOR(y, 1, n + 1) {
re(state[y]);
if (state[y] < 0) {
lev[y] = -state[y];
int z = getPar(y - 1, lev[y] - 1);
std::cin >> n;
for (int i = 1; i <= n; i++) {
std::cin >> state[i];
if (state[i] < 0) {
lev[i] = -state[i];
int z = get_par(i - 1, lev[i] - 1);
assert(z); // must be something to undo
par[y][0] = getPar(z - 1, lev[y] - 1);
assert(lev[y] > lev[par[y][0]]); // levels of ops in active path
// are strictly decreasing
FOR(j, 1, 19)
par[y][j] = par[par[y][j - 1]][j - 1]; // prep binary jumps
par[i][0] = get_par(z - 1, lev[i] - 1);

// levels of ops in active path are strictly decreasing
assert(lev[i] > lev[par[i][0]]);

for (int j = 1; j < MAX_D; j++) {
par[i][j] = par[par[i][j - 1]][j - 1]; // prepare binary jumps
}
}
ps(state[getPar(y, 0)]);
// current active path is y, par[y], par[par[y]], ...
std::cout << state[get_par(i, 0)] << '\n';
// current active path is i, par[i], par[par[i]], ...
}
}
```
</CPPSection>
<PySection>
```py
import math

MAX_N = 300001
MAX_D = math.ceil(math.log2(MAX_N))

state = [0] * MAX_N
par = [[0] * MAX_D for _ in range(MAX_N)]
lev = [0] * MAX_N


def get_par(x: int, max_lev: int) -> int:
"""get last op on active path of x with lev <= max_lev"""
if lev[x] <= max_lev:
return x
for i in range(MAX_D - 1, -1, -1):
if lev[par[x][i]] > max_lev:
x = par[x][i]
return par[x][0]


n = int(input())

for i in range(1, n + 1):
state[i] = int(input())

if state[i] < 0:
lev[i] = -state[i]
z = get_par(i - 1, lev[i] - 1)

# must be something to undo
assert z > 0

par[i][0] = get_par(z - 1, lev[i] - 1)

# levels of ops in active path are strictly decreasing
assert lev[i] > lev[par[i][0]]

# prepare binary jumps
for j in range(1, MAX_D):
par[i][j] = par[par[i][j - 1]][j - 1]

# current active path is i, par[i], par[par[i]], ...
print(state[get_par(i, 0)])
```
</PySection>
</LanguageSection>

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