Consider all triplets and increment result whenever sum of a triplet is n .
for i in range ( n + 1 ) : NEW_LINE INDENT for j in range ( n + 1 ) : NEW_LINE INDENT for k in range ( n + 1 ) : NEW_LINE INDENT if i + j + k == n : NEW_LINE INDENT result += 1 NEW_LINE DEDENT DEDENT DEDENT DEDENT return result NEW_LINE