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OI-codes/S2OJ/1200/1200.cpp

53 lines
1.1 KiB
C++

#include <iostream>
#include <vector>
using std::cin;
using std::cout;
using std::endl;
const long long mod = 281474976710656;
int n;
long long ans;
char g[505][505];
void dfs1(int, int, std::vector<int>);
long long dfs2(int, int, std::vector<int>, int, int, std::vector<int>);
int main() {
cin >> n;
for (int i = 1; i <= n; i++) {
cin >> g[i] + 1;
}
dfs1(1, 1, std::vector<int>());
cout << ans << endl;
return 0;
}
void dfs1(int x, int y, std::vector<int> s) {
if (x < 1 || x > n || y < 1 || y > n) return;
s.push_back(g[x][y] - 'A');
if (x + y == n + 1) {
ans = (ans + dfs2(n, n, std::vector<int>(), x, y, s)) % mod;
return;
}
dfs1(x + 1, y, s);
dfs1(x, y + 1, s);
}
long long dfs2(
int x,
int y,
std::vector<int> s,
int lx,
int ly,
std::vector<int> t) {
if (x < lx || x > n || y < ly || y > n) return 0;
s.push_back(g[x][y] - 'A');
long long res = 0;
if (x == lx && y == ly && s == t) return 1;
res += dfs2(x - 1, y, s, lx, ly, t);
res += dfs2(x, y - 1, s, lx, ly, t);
return res;
}