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  1. #include <bits/stdc++.h>
  2. using namespace std;
  3. int n;
  4. int t[20][20];
  5. map<int, int> cnt[20][20];
  6. long long ans = 0;
  7. void dfs_first(int i, int j, int x) {
  8.     if (i + j == n - 1) {
  9.         cnt[i][j][x]++;
  10.         return;
  11.     }
  12.     if (i + 1 < n) dfs_first(i + 1, j, x ^ t[i][j]);
  13.     if (j + 1 < n) dfs_first(i, j + 1, x ^ t[i][j]);
  14. }
  15. void dfs_second(int i, int j, int x) {
  16.     if (i + j == n - 1) {
  17.         if (cnt[i][j].count(x ^ t[i][j]))
  18.             ans += cnt[i][j][x ^ t[i][j]];
  19.         return;
  20.     }
  21.     if (i - 1 >= 0) dfs_second(i - 1, j, x ^ t[i][j]);
  22.     if (j - 1 >= 0) dfs_second(i, j - 1, x ^ t[i][j]);
  23. }
  24. int main() {
  25.     cin >> n;
  26.     for (int i = 0; i < n; ++i)
  27.         for (int j = 0; j < n; ++j)
  28.             cin >> t[i][j];
  29.     dfs_first(0, 0, 0);
  30.     dfs_second(n - 1, n - 1, 0); 
  31.    cout << ans << '\n';
  32.     return 0;
  33. }
Success #stdin #stdout 0.01s 5320KB
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https://ideone.com/uTlVWZ
language:
C++14 (gcc 8.3)
created:
2 days ago
visibility:
public

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