Informal mathematical proofs admit and require interpretation while formal logic proofs suppress (abstract from) meanings. The former is closely related to problem solving and computer programming. The latter, which is commonly used for proving program correctness, complicates this procedure because it separates problem solving from programming. A constructive mathematical proof in finite discrete mathematics of an existential theorem is a computer program if the pertinent data structures and functions are expressed in a programming language. Several detailed examples of graph theoretical problems and theorems are presented along with their constructive proofs and corresponding programs.