Editing Longest common subsequence (section)

=== Reading out all LCSs ===
If choosing <math>x_i</math> and <math>y_j</math> would give an equally long result, read out both resulting subsequences. This is returned as a set by this function. Notice that this function is not polynomial, as it might branch in almost every step if the strings are similar.

 '''function''' backtrackAll(C[0..m,0..n], X[1..m], Y[1..n], i, j)
     '''if''' i = 0 '''or''' j = 0
         '''return''' {""}
     '''if''' X[i] = Y[j]
         '''return''' {Z + X[i] '''for all''' Z '''in''' backtrackAll(C, X, Y, i-1, j-1)}
     R := {}
     '''if''' C[i,j-1] ≥ C[i-1,j]
         R := backtrackAll(C, X, Y, i, j-1)
     '''if''' C[i-1,j] ≥ C[i,j-1]
         R := R ∪ backtrackAll(C, X, Y, i-1, j)
     '''return''' R