#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using db = long double; // or double, if TL is tight
using str = string; // yay python!
// pairs
using pi = pair<int,int>;
using pl = pair<ll,ll>;
using pd = pair<db,db>;
#define mp make_pair
#define f first
#define s second
#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>;
using vi = V<int>;
using vb = V<bool>;
using vl = V<ll>;
using vd = V<db>;
using vs = V<str>;
using vpi = V<pi>;
using vpl = V<pl>;
using vpd = V<pd>;
// 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 pb push_back
#define eb emplace_back
#define ft front()
#define bk back()
#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)); }
tcT> int upb(V<T>& a, const T& b) { return int(ub(all(a),b)-bg(a)); }
// loops
#define F1R(i, a) FOR(i, 1, a+1)
#define FOR(i,a,b) for (ll 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 rep(a) F0R(_,a)
#define each(a,x) for (auto& a: x)
#define FIO ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
#define PR0(A,n) { cout << #A << " = "; rep(n) cout << A[_] << ' '; cout << endl; }
const int MOD = 1e9+7; // 998244353;
const int MX = 2e5+5;
const ll INF = 1e18; // not too close to LLONG_MAX
const db PI = acos((db)-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; } // set a = max(a,b)
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
#define tcTUU tcT, class ...U
inline namespace Helpers {
//////////// is_iterable
// https://stackoverflow.com/questions/13830158/check-if-a-variable-type-is-iterable
// this gets used only when we can call begin() and end() on that type
tcT, class = void> struct is_iterable : false_type {};
tcT> struct is_iterable<T, void_t<decltype(begin(declval<T>())),
decltype(end(declval<T>()))
>
> : true_type {};
tcT> constexpr bool is_iterable_v = is_iterable<T>::value;
//////////// is_readable
tcT, class = void> struct is_readable : false_type {};
tcT> struct is_readable<T,
typename std::enable_if_t<
is_same_v<decltype(cin >> declval<T&>()), istream&>
>
> : true_type {};
tcT> constexpr bool is_readable_v = is_readable<T>::value;
//////////// is_printable
// // https://nafe.es/posts/2020-02-29-is-printable/
tcT, class = void> struct is_printable : false_type {};
tcT> struct is_printable<T,
typename std::enable_if_t<
is_same_v<decltype(cout << declval<T>()), ostream&>
>
> : true_type {};
tcT> constexpr bool is_printable_v = is_printable<T>::value;
}
inline namespace Input {
tcT> constexpr bool needs_input_v = !is_readable_v<T> && is_iterable_v<T>;
tcTUU> void re(T& t, U&... u);
tcTU> void re(pair<T,U>& p); // pairs
// re: read
tcT> typename enable_if<is_readable_v<T>,void>::type re(T& x) { cin >> x; } // default
tcT> void re(complex<T>& c) { T a,b; re(a,b); c = {a,b}; } // complex
tcT> typename enable_if<needs_input_v<T>,void>::type re(T& i); // ex. vectors, arrays
tcTU> void re(pair<T,U>& p) { re(p.f,p.s); }
tcT> typename enable_if<needs_input_v<T>,void>::type re(T& i) {
each(x,i) re(x); }
tcTUU> void re(T& t, U&... u) { re(t); re(u...); } // read multiple
// rv: resize and read vectors
void rv(size_t) {}
tcTUU> void rv(size_t N, V<T>& t, U&... u);
template<class...U> void rv(size_t, size_t N2, U&... u);
tcTUU> void rv(size_t N, V<T>& t, U&... u) {
t.rsz(N); re(t);
rv(N,u...); }
template<class...U> void rv(size_t, size_t N2, U&... u) {
rv(N2,u...); }
// dumb shortcuts to read in ints
void decrement() {} // subtract one from each
tcTUU> void decrement(T& t, U&... u) { --t; decrement(u...); }
#define ints(...) int __VA_ARGS__; re(__VA_ARGS__);
#define lls(...) ll __VA_ARGS__; re(__VA_ARGS__);
#define strs(...) str __VA_ARGS__; re(__VA_ARGS__);
#define int1(...) ints(__VA_ARGS__); decrement(__VA_ARGS__);
}
inline namespace ToString {
tcT> constexpr bool needs_output_v = !is_printable_v<T> && is_iterable_v<T>;
// ts: string representation to print
tcT> typename enable_if<is_printable_v<T>,str>::type ts(T v) {
stringstream ss; ss << fixed << setprecision(15) << v;
return ss.str(); } // default
tcT> str bit_vec(T t) { // bit vector to string
str res = "{"; F0R(i,sz(t)) res += ts(t[i]);
res += "}"; return res; }
str ts(V<bool> v) { return bit_vec(v); }
template<size_t SZ> str ts(bitset<SZ> b) { return bit_vec(b); } // bit vector
tcTU> str ts(pair<T,U> p); // pairs
tcT> typename enable_if<needs_output_v<T>,str>::type ts(T v); // vectors, arrays
tcTU> str ts(pair<T,U> p) { return "("+ts(p.f)+", "+ts(p.s)+")"; }
tcT> typename enable_if<is_iterable_v<T>,str>::type ts_sep(T v, str sep) {
// convert container to string w/ separator sep
bool fst = 1; str res = "";
for (const auto& x: v) {
if (!fst) res += sep;
fst = 0; res += ts(x);
}
return res;
}
tcT> typename enable_if<needs_output_v<T>,str>::type ts(T v) {
return "{"+ts_sep(v,", ")+"}"; }
// for nested DS
template<int, class T> typename enable_if<!needs_output_v<T>,vs>::type
ts_lev(const T& v) { return {ts(v)}; }
template<int lev, class T> typename enable_if<needs_output_v<T>,vs>::type
ts_lev(const T& v) {
if (lev == 0 || !sz(v)) return {ts(v)};
vs res;
for (const auto& t: v) {
if (sz(res)) res.bk += ",";
vs tmp = ts_lev<lev-1>(t);
res.ins(end(res),all(tmp));
}
F0R(i,sz(res)) {
str bef = " "; if (i == 0) bef = "{";
res[i] = bef+res[i];
}
res.bk += "}";
return res;
}
}
inline namespace Output {
template<class T> void pr_sep(ostream& os, str, const T& t) { os << ts(t); }
template<class T, class... U> void pr_sep(ostream& os, str sep, const T& t, const U&... u) {
pr_sep(os,sep,t); os << sep; pr_sep(os,sep,u...); }
// print w/ no spaces
template<class ...T> void pr(const T&... t) { pr_sep(cout,"",t...); }
// print w/ spaces, end with newline
void ps() { cout << "\n"; }
template<class ...T> void ps(const T&... t) { pr_sep(cout," ",t...); ps(); }
// debug to cerr
template<class ...T> void dbg_out(const T&... t) {
pr_sep(cerr," | ",t...); cerr << endl; }
void loc_info(int line, str names) {
cerr << "Line(" << line << ") -> [" << names << "]: "; }
template<int lev, class T> void dbgl_out(const T& t) {
cerr << "\n\n" << ts_sep(ts_lev<lev>(t),"\n") << "\n" << endl; }
#ifdef LOCAL
#define dbg(...) loc_info(__LINE__,#__VA_ARGS__), dbg_out(__VA_ARGS__)
#define dbgl(lev,x) loc_info(__LINE__,#x), dbgl_out<lev>(x)
#else // don't actually submit with this
#define dbg(...) 0
#define dbgl(lev,x) 0
#endif
const clock_t beg = clock();
#define dbg_time() dbg((db)(clock()-beg)/CLOCKS_PER_SEC)
}
inline namespace FileIO {
void setIn(str s) { freopen(s.c_str(),"r",stdin); }
void setOut(str s) { freopen(s.c_str(),"w",stdout); }
void setIO(str s = "") {
cin.tie(0)->sync_with_stdio(0); // unsync C / C++ I/O streams
// 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 old USACO
}
}
//struct Item {
// int node;
// ll cost;
// bool discount;
//
// Item(int _node, ll _cost, bool _discount) {
// node = _node;
// cost = _cost;
// discount = _discount;
// }
//
// inline const bool operator<(const Item& other) const {
// if (discount == other.discount) {
// return cost > other.cost;
// }
// return discount > other.discount;
// }
//};
V<vl> g;
void solve(){
lls(H, W);
vs v(H); re(v);
deque<pl> d;
V<vl> dp(H, vl(W+1, 0));
dp[0][0]=1;
d.pb({0, 0});
ll ans=0;
while(!d.empty())
{
pl p = d.front();
ans=max(ans, dp[p.f][p.s]);
d.pop_front();
F0R(i, 4)
{
int x = p.first + dx[i], y = p.second + dy[i];
if(x>=0 && x<H && y<W && y>=0 && v[x][y]!='.')
{
ll n = dp[p.f][p.s]+(v[p.f][p.s]!=v[x][y]);
if(dp[x][y]==0)
{
dp[p.f+dx[i]][p.s+dy[i]] = max(dp[x][y], n);
if(v[p.f][p.s]!=v[x][y])
d.pb({x, y});
else
d.push_front({x, y});
}
}
}
}
ps(ans);
}
int main() {
// setIO();
// int TC; re(TC);
// FOR(i,1,TC+1) {
// pr("Case #",i,": ");
solve();
// }
// you should actually read the stuff at the bottom
}
/* stuff you should look for
* int overflow, array bounds
* special cases (n=1?)
* do smth instead of nothing and stay organized
* WRITE STUFF DOWN
* DON'T GET STUCK ON ONE APPROACH
* even if it's slow, try it out
* Look for any oddities in the prompt
* Its prob DP
* Make it easy for yourself
* disorganized? Make a struct
*/
Compilation message
tracks.cpp: In function 'void FileIO::setIn(str)':
tracks.cpp:249:30: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
249 | void setIn(str s) { freopen(s.c_str(),"r",stdin); }
| ~~~~~~~^~~~~~~~~~~~~~~~~~~~~
tracks.cpp: In function 'void FileIO::setOut(str)':
tracks.cpp:250:30: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
250 | void setOut(str s) { freopen(s.c_str(),"w",stdout); }
| ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
18 ms |
3020 KB |
Output is correct |
| 2 |
Correct |
1 ms |
204 KB |
Output is correct |
| 3 |
Correct |
1 ms |
332 KB |
Output is correct |
| 4 |
Correct |
12 ms |
2356 KB |
Output is correct |
| 5 |
Correct |
4 ms |
1100 KB |
Output is correct |
| 6 |
Correct |
1 ms |
204 KB |
Output is correct |
| 7 |
Correct |
1 ms |
204 KB |
Output is correct |
| 8 |
Correct |
1 ms |
332 KB |
Output is correct |
| 9 |
Correct |
1 ms |
332 KB |
Output is correct |
| 10 |
Correct |
4 ms |
972 KB |
Output is correct |
| 11 |
Correct |
3 ms |
844 KB |
Output is correct |
| 12 |
Correct |
7 ms |
1284 KB |
Output is correct |
| 13 |
Correct |
4 ms |
1208 KB |
Output is correct |
| 14 |
Correct |
5 ms |
1100 KB |
Output is correct |
| 15 |
Correct |
18 ms |
3072 KB |
Output is correct |
| 16 |
Correct |
19 ms |
3044 KB |
Output is correct |
| 17 |
Correct |
15 ms |
2912 KB |
Output is correct |
| 18 |
Correct |
11 ms |
2252 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
3 ms |
948 KB |
Output is correct |
| 2 |
Correct |
85 ms |
16472 KB |
Output is correct |
| 3 |
Correct |
601 ms |
163964 KB |
Output is correct |
| 4 |
Correct |
165 ms |
40580 KB |
Output is correct |
| 5 |
Correct |
437 ms |
90852 KB |
Output is correct |
| 6 |
Correct |
1235 ms |
192072 KB |
Output is correct |
| 7 |
Correct |
3 ms |
972 KB |
Output is correct |
| 8 |
Correct |
3 ms |
972 KB |
Output is correct |
| 9 |
Correct |
3 ms |
972 KB |
Output is correct |
| 10 |
Correct |
2 ms |
588 KB |
Output is correct |
| 11 |
Correct |
3 ms |
972 KB |
Output is correct |
| 12 |
Correct |
2 ms |
460 KB |
Output is correct |
| 13 |
Correct |
80 ms |
16524 KB |
Output is correct |
| 14 |
Correct |
50 ms |
10020 KB |
Output is correct |
| 15 |
Correct |
49 ms |
10960 KB |
Output is correct |
| 16 |
Correct |
38 ms |
6664 KB |
Output is correct |
| 17 |
Correct |
218 ms |
43784 KB |
Output is correct |
| 18 |
Correct |
185 ms |
43200 KB |
Output is correct |
| 19 |
Correct |
161 ms |
40552 KB |
Output is correct |
| 20 |
Correct |
132 ms |
37404 KB |
Output is correct |
| 21 |
Correct |
348 ms |
93780 KB |
Output is correct |
| 22 |
Correct |
374 ms |
90920 KB |
Output is correct |
| 23 |
Correct |
415 ms |
78156 KB |
Output is correct |
| 24 |
Correct |
337 ms |
92212 KB |
Output is correct |
| 25 |
Correct |
890 ms |
164060 KB |
Output is correct |
| 26 |
Correct |
757 ms |
218556 KB |
Output is correct |
| 27 |
Correct |
1022 ms |
233268 KB |
Output is correct |
| 28 |
Correct |
1146 ms |
192064 KB |
Output is correct |
| 29 |
Correct |
1134 ms |
187316 KB |
Output is correct |
| 30 |
Correct |
1059 ms |
199168 KB |
Output is correct |
| 31 |
Correct |
856 ms |
102288 KB |
Output is correct |
| 32 |
Correct |
960 ms |
212712 KB |
Output is correct |
