n/=2;
dp[n][n*9];
dp[i][j] = dp[i-1][j]+dp[i-1][j-1] + ... + dp[i-1][j-9];
ans = dp[n][0]*dp[n][0] + ... + dp[n][n*9]*dp[n][n*9];

Edited by author 17.09.2021 19:12

Edited by author 17.09.2021 19:12