Given $$$N$$$ strings, we need to count how many pairs $$$1$$$ <= i, j <= $$$N$$$ exists such that s[i] + s[j] is a plaindrome. Can anyone suggest an efficient approach for solving this problem?
1 <= $$$N$$$ <= 2000
1 <= |s_i <= 1000

My approach is to precompute hashes of the given strings. Now iterate over all pairs i, j now we want to concatenate the two strings s[i] + s[j].