結果
| 問題 |
No.13 囲みたい！
|
| コンテスト | |
| ユーザー |
 Demystify
|
| 提出日時 | 2022-04-17 20:44:24 |
| 言語 | C++17 (gcc 13.3.0 + boost 1.87.0) |
| 結果 |
AC
|
| 実行時間 | 4 ms / 5,000 ms |
| コード長 | 8,555 bytes |
| コンパイル時間 | 2,438 ms |
| コンパイル使用メモリ | 211,460 KB |
| 最終ジャッジ日時 | 2025-01-28 18:58:58 |
|
ジャッジサーバーID （参考情報） |
judge2 / judge1 |
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| ファイルパターン | 結果 |
|---|---|
| other | AC * 16 |
ソースコード
#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ld = long double;
// --------------------------------------------------------
#define FOR(i,l,r) for (ll i = (l); i < (r); ++i)
#define RFOR(i,l,r) for (ll i = (r)-1; (l) <= i; --i)
#define REP(i,n) FOR(i,0,n)
#define RREP(i,n) RFOR(i,0,n)
#define ALL(c) (c).begin(), (c).end()
#define RALL(c) (c).rbegin(), (c).rend()
#define SORT(c) sort(ALL(c))
#define RSORT(c) sort(RALL(c))
#define MIN(c) *min_element(ALL(c))
#define MAX(c) *max_element(ALL(c))
#define SUMLL(c) accumulate(ALL(c), 0LL)
#define COUNT(c,v) count(ALL(c),(v))
#define SZ(c) ((ll)(c).size())
#define BIT(b,i) (((b)>>(i)) & 1)
#define PCNT(b) __builtin_popcountll(b)
#define P0(i) (((i) & 1) == 0)
#define P1(i) (((i) & 1) == 1)
#ifdef _LOCAL
#define debug_bar cerr << "--------------------\n";
#define debug(x) cerr << "l." << __LINE__ << " : " << #x << " = " << (x) << '\n'
#define debug_pair(x) cerr << "l." << __LINE__ << " : " << #x << " = (" << x.first << "," << x.second << ")\n";
template<class T> void debug_line(const vector<T>& ans, int l, int r, int L = 0) { cerr << "l." << L << " :"; for (int i = l; i < r; i++) { cerr << ' ' << ans[i]; } cerr << '\n'; }
#else
#define cerr if (false) cerr
#define debug_bar
#define debug(x)
#define debug_pair(x)
template<class T> void debug_line([[maybe_unused]] const vector<T>& ans, [[maybe_unused]] int l, [[maybe_unused]] int r, [[maybe_unused]] int L = 0) {}
#endif
template<class... T> void input(T&... a) { (cin >> ... >> a); }
void print() { cout << '\n'; }
template<class T> void print(const T& a) { cout << a << '\n'; }
template<class T, class... Ts> void print(const T& a, const Ts&... b) { cout << a; (cout << ... << (cout << ' ', b)); cout << '\n'; }
template<class T> void cout_line(const vector<T>& ans, int l, int r) { for (int i = l; i < r; i++) { if (i != l) { cout << ' '; } cout << ans[i]; } cout << '\n'; }
template<class T> bool chmin(T& a, const T b) { if (b < a) { a = b; return 1; } return 0; }
template<class T> bool chmax(T& a, const T b) { if (a < b) { a = b; return 1; } return 0; }
pair<ll,ll> divmod(ll a, ll b) { assert(a >= 0 && b > 0); return make_pair(a / b, a % b); }
ll mod(ll x, ll m) { assert(m != 0); return (x % m + m) % m; }
ll llceil(ll a, ll b) { if (b < 0) { return llceil(-a, -b); } assert(b > 0); return (a < 0 ? a / b : (a + b - 1) / b); }
ll llfloor(ll a, ll b) { if (b < 0) { return llfloor(-a, -b); } assert(b > 0); return (a > 0 ? a / b : (a - b + 1) / b); }
ll llpow(ll x, ll n) { assert(n >= 0); if (n == 0) { return 1; }; ll res = llpow(x, n>>1); res *= res; if (n & 1) { res *= x; } return res; }
ll bitlen(ll b) { if (b <= 0) { return 0; } return (64LL - __builtin_clzll(b)); }
ll digit_len(ll n) { assert(n >= 0); if (n == 0) { return 1; } ll sum = 0; while (n > 0) { sum++; n /= 10; } return sum; }
ll digit_sum(ll n) { assert(n >= 0); ll sum = 0; while (n > 0) { sum += n % 10; n /= 10; } return sum; }
ll digit_prod(ll n) { assert(n >= 0); if (n == 0) { return 0; } ll prod = 1; while (n > 0) { prod *= n % 10; n /= 10; } return prod; }
ll xor_sum(ll x) { assert(0 <= x); switch (x % 4) { case 0: return x; case 1: return 1; case 2: return x ^ 1; case 3: return 0; } assert(false); }
string toupper(const string& S) { string T(S); for (int i = 0; i < (int)T.size(); i++) { T[i] = toupper(T[i]); } return T; }
string tolower(const string& S) { string T(S); for (int i = 0; i < (int)T.size(); i++) { T[i] = tolower(T[i]); } return T; }
int a2i(const char& c) { assert(islower(c)); return (c - 'a'); }
int A2i(const char& c) { assert(isupper(c)); return (c - 'A'); }
int d2i(const char& d) { assert(isdigit(d)); return (d - '0'); }
char i2a(const int& i) { assert(0 <= i && i < 26); return ('a' + i); }
char i2A(const int& i) { assert(0 <= i && i < 26); return ('A' + i); }
char i2d(const int& i) { assert(0 <= i && i <= 9); return ('0' + i); }
using P = pair<ll,ll>;
using VP = vector<P>;
using VVP = vector<VP>;
using VS = vector<string>;
using VVS = vector<VS>;
using VI = vector<int>;
using VVI = vector<VI>;
using VVVI = vector<VVI>;
using VLL = vector<ll>;
using VVLL = vector<VLL>;
using VVVLL = vector<VVLL>;
using VB = vector<bool>;
using VVB = vector<VB>;
using VVVB = vector<VVB>;
using VD = vector<double>;
using VVD = vector<VD>;
using VVVD = vector<VVD>;
using VLD = vector<ld>;
using VVLD = vector<VLD>;
using VVVLD = vector<VVLD>;
const ld EPS = 1e-10;
const ld PI = acosl(-1.0);
constexpr ll MOD = 1000000007;
// constexpr ll MOD = 998244353;
constexpr int inf = (1 << 30) - 1; // 1073741824 - 1
constexpr ll INF = (1LL << 62) - 1; // 4611686018427387904 - 1
// --------------------------------------------------------
// #include <atcoder/all>
// using namespace atcoder;
// References:
// <https://github.com/atcoder/ac-library/blob/v1.4/atcoder/dsu.hpp>
// <https://en.wikipedia.org/wiki/Disjoint-set_data_structure>
// Disjoint-set data structure (Union Find)
//
struct dsu {
public:
dsu() : N(0) {}
explicit dsu(int n) : N(n), parent_or_size(n, -1), n_edge(n, 0) {}
// 辺 (a, b) を張ってマージ成否を返す : amortized O(α(N))
bool merge(int a, int b) {
assert(0 <= a && a < N);
assert(0 <= b && b < N);
int x = leader(a), y = leader(b);
if (x == y) { n_edge[x]++; return false; }
if (-parent_or_size[x] < -parent_or_size[y]) { swap(x, y); }
parent_or_size[x] += parent_or_size[y];
parent_or_size[y] = x;
n_edge[x] += n_edge[y] + 1;
return true;
}
// 頂点 a, b が連結か判定する : amortized O(α(N))
bool same(int a, int b) {
assert(0 <= a && a < N);
assert(0 <= b && b < N);
return leader(a) == leader(b);
}
// 頂点 a の属する連結成分のルートを返す : amortized O(α(N))
int leader(int a) {
assert(0 <= a && a < N);
if (parent_or_size[a] < 0) { return a; }
return parent_or_size[a] = leader(parent_or_size[a]);
}
// 頂点 a が属する連結成分のサイズを返す : amortized O(α(N))
int size(int a) {
assert(0 <= a && a < N);
return -parent_or_size[leader(a)];
}
// a が属する連結成分の辺の数を返す : amortized O(α(N))
int size_e(int a) {
assert(0 <= a && a < N);
return n_edge[leader(a)];
}
// 「一つの連結成分の頂点番号リスト」のリストを返す : O(N)
vector<vector<int>> groups() {
vector<int> leader_buf(N), group_size(N);
for (int i = 0; i < N; i++) {
leader_buf[i] = leader(i);
group_size[leader_buf[i]]++;
}
vector<vector<int>> result(N);
for (int i = 0; i < N; i++) {
result[i].reserve(group_size[i]);
}
for (int i = 0; i < N; i++) {
result[leader_buf[i]].push_back(i);
}
result.erase(
remove_if(result.begin(), result.end(),
[&](const vector<int>& v) { return v.empty(); }),
result.end());
return result;
}
private:
int N;
// [x < 0] -x が連結成分のサイズに対応
// [0 <= x] x が parent に対応
vector<int> parent_or_size;
vector<int> n_edge;
};
int main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
cout << fixed << setprecision(15);
ll W, H; input(W, H);
VVLL A(H,VLL(W)); REP(h,H) REP(w,W) input(A[h][w]);
auto on_grid = [&](ll h, ll w) -> bool { return (0 <= h && h < H && 0 <= w && w < W); };
auto hw2i = [&](ll h, ll w) -> ll { return h * W + w; };
const VLL dh4 = {0, 1, 0,-1}; // 右,下,左,上
const VLL dw4 = {1, 0,-1, 0};
auto output = [](string ans) -> void { cout << ans << '\n'; exit(0); };
dsu uf(W*H);
VVB vis(H, VB(W, false));
REP(h,H) REP(w,W) if (not vis[h][w]) {
int a = A[h][w];
auto dfs = [&](auto&& self, ll h, ll w, ll p) -> void {
ll u = hw2i(h, w);
vis[h][w] = true;
REP(d,4) {
ll hh = h + dh4[d];
ll ww = w + dw4[d];
ll v = hw2i(hh, ww);
if (v == p) continue;
if (not on_grid(hh, ww)) continue;
if (A[hh][ww] != a) continue;
if (uf.same(u, v)) output("possible");
uf.merge(u, v);
self(self, hh, ww, u);
}
};
dfs(dfs, h, w, -1);
}
output("impossible");
return 0;
}