結果

問題 No.1916 Making Palindrome on Gird
ユーザー momoharamomohara
提出日時 2022-04-29 22:37:34
言語 C++17
(gcc 13.3.0 + boost 1.87.0)
結果
AC  
実行時間 349 ms / 3,000 ms
コード長 6,295 bytes
コンパイル時間 2,417 ms
コンパイル使用メモリ 212,540 KB
最終ジャッジ日時 2025-01-28 23:25:50
ジャッジサーバーID
(参考情報)
judge4 / judge2
このコードへのチャレンジ
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ファイルパターン 結果
sample AC * 3
other AC * 30
権限があれば一括ダウンロードができます

ソースコード

diff #
プレゼンテーションモードにする

#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ull = unsigned long long;
using ld = long double;
using P = pair<ll, ll>;
using tp = tuple<ll, ll, ll>;
template <class T>
using vec = vector<T>;
template <class T>
using vvec = vector<vec<T>>;
#define all(hoge) (hoge).begin(), (hoge).end()
#define en '\n'
#define rep(i, m, n) for(ll i = (ll)(m); i < (ll)(n); ++i)
#define rep2(i, m, n) for(ll i = (ll)(n)-1; i >= (ll)(m); --i)
#define REP(i, n) rep(i, 0, n)
#define REP2(i, n) rep2(i, 0, n)
constexpr long long INF = 1LL << 60;
constexpr int INF_INT = 1 << 25;
constexpr long long MOD = (ll)1e9 + 7;
// constexpr long long MOD = 998244353LL;
static const ld pi = 3.141592653589793L;
#pragma GCC target("avx2")
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
template <class T>
inline bool chmin(T &a, T b) {
if(a > b) {
a = b;
return true;
}
return false;
}
template <class T>
inline bool chmax(T &a, T b) {
if(a < b) {
a = b;
return true;
}
return false;
}
//
struct Edge {
int to, rev;
ll cap;
Edge(int _to, int _rev, ll _cap) : to(_to), rev(_rev), cap(_cap) {}
};
typedef vector<Edge> Edges;
typedef vector<Edges> Graph;
void add_edge(Graph &G, int from, int to, ll cap, bool revFlag, ll revCap) {
G[from].push_back(Edge(to, (int)G[to].size(), cap));
if(revFlag)
G[to].push_back(Edge(from, (int)G[from].size() - 1, revCap));
}
template <int mod>
struct ModInt {
int x;
ModInt() : x(0) {}
ModInt(int64_t y) : x(y >= 0 ? y % mod : (mod - (-y) % mod) % mod) {}
ModInt &operator+=(const ModInt &p) {
if((x += p.x) >= mod)
x -= mod;
return *this;
}
ModInt &operator-=(const ModInt &p) {
if((x += mod - p.x) >= mod)
x -= mod;
return *this;
}
ModInt &operator*=(const ModInt &p) {
x = (int)(1LL * x * p.x % mod);
return *this;
}
ModInt &operator/=(const ModInt &p) {
*this *= p.inverse();
return *this;
}
ModInt operator-() const { return ModInt(-x); }
ModInt operator+(const ModInt &p) const { return ModInt(*this) += p; }
ModInt operator-(const ModInt &p) const { return ModInt(*this) -= p; }
ModInt operator*(const ModInt &p) const { return ModInt(*this) *= p; }
ModInt operator/(const ModInt &p) const { return ModInt(*this) /= p; }
bool operator==(const ModInt &p) const { return x == p.x; }
bool operator!=(const ModInt &p) const { return x != p.x; }
ModInt inverse() const {
int a = x, b = mod, u = 1, v = 0, t;
while(b > 0) {
t = a / b;
swap(a -= t * b, b);
swap(u -= t * v, v);
}
return ModInt(u);
}
ModInt pow(int64_t n) const {
ModInt ret(1), mul(x);
while(n > 0) {
if(n & 1)
ret *= mul;
mul *= mul;
n >>= 1;
}
return ret;
}
friend ostream &operator<<(ostream &os, const ModInt &p) {
return os << p.x;
}
friend istream &operator>>(istream &is, ModInt &a) {
int64_t t;
is >> t;
a = ModInt<mod>(t);
return (is);
}
static int get_mod() { return mod; }
};
using mint = ModInt<MOD>;
void solve() {
ll h, w;
cin >> h >> w;
vec<string> s(h);
REP(i, h) {
cin >> s[i];
}
if(s[0][0] != s[h - 1][w - 1]) {
cout << 0 << en;
return;
}
if(h + w <= 3) {
cout << (s[0][0] == s[h - 1][w - 1]) << en;
return;
}
vector dp(h + w, vector(h + w, vector(h + w, mint(0))));
dp[0][h][w] = 1; // s[0][0]s[h-1][w-1]
int d = (h + w - 1 + 1) / 2 - 1;
ll dx[2] = {1, 0};
ll dy[2] = {0, 1};
mint ans = 0;
REP(i, d) {
// cout << "d:" << i << en;
REP(j, h + w) {
REP(k, h + w) {
if(dp[i][j][k].x == 0)
continue;
int x1 = (i + j - h) / 2;
int y1 = (i - j + h) / 2;
int x2 = (h + w - 1 - i + k - h) / 2;
int y2 = (h + w - 1 - i - k + h) / 2;
// cout << x1 << " " << y1 << " " << x2 << " " << y2 << en;
REP(v1, 2) {
ll nx1 = x1 + dx[v1];
ll ny1 = y1 + dy[v1];
if(nx1 < 0 or nx1 >= w or ny1 < 0 or ny1 >= h)
continue;
REP(v2, 2) {
ll nx2 = x2 - dx[v2];
ll ny2 = y2 - dy[v2];
if(nx2 < 0 or nx2 >= w or ny2 < 0 or ny2 >= h)
continue;
if(s[ny1][nx1] != s[ny2][nx2])
continue;
ll nj = nx1 - ny1 + h;
ll nk = nx2 - ny2 + h;
// cout << nx1 << " " << ny1 << " " << nx2 << " " << ny2 << en;
if(i + 1 == d) {
if((h + w - 1) % 2) {
if(nx1 == nx2 and ny1 == ny2)
ans += dp[i][j][k];
} else {
if(abs(nx2 - nx1) + abs(ny2 - ny1) <= 1)
ans += dp[i][j][k];
}
continue;
}
dp[i + 1][nj][nk] += dp[i][j][k];
}
}
}
}
// REP(j, h + w) {
// REP(k, h + w) {
// cout << dp[i][j][k] << " ";
// }
// cout << en;
// }
}
// REP(i, d) {
// cout << "d:" << i << en;
// REP(j, h + w) {
// REP(k, h + w) {
// cout << dp[i][j][k] << " ";
// }
// cout << en;
// }
// cout << en;
// }
cout << ans << en;
}
int main() {
ios::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
// cout << fixed << setprecision(10);
// ll t;
// cin >> t;
// REP(i, t - 1) {
// solve();
// }
solve();
return 0;
}
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