Please see some of the prestigious journals in Discrete Mathematics:
Combinatorica (Springer)
Discrete Mathematics (Elsevier)
Discrete Applied Mathematics (Elsevier)
Discrete Mathematics and Theoretical Computer Science
European Journal of Combinatorics
Journal of Combinatorial Designs (Wiley)
Journal of Combinatorial Theory Series A (Academic Press)
Journal of Combinatorial Theory Series B (Academic Press)
Journal of Graph Theory (Wiley)
There are more prestigious journals which are included in SCIE, but not in SCI. You can see those journals from the website ip-science.thomsonreuters.com/mjl/
journal of theoretic computer science. journal of appllied soft computing. etc of elsevier. you can try. but litle time you need. better contact a reputer well known researcher in your line and request him to evaluate your paper, acknowledge his name in the paper and take advise from him where then to submit.