# Suggested problems

## PCB-FS technical drawing

June 15, 2022, 12:23 p.m. by FSPCBA

## Biological Motivation

1. The circumference of the circle should be very obvious.

For Feisheng circular boards, for chips with IC pin spacing less than 0.65mm, there must be a signal that can significantly change the chip position to the longest side of the IC. If there are islands on both sides of the https://www.mediafire.com/file/qk2wmx1bb9qsndn/www_fs-pcba_com_.pdf/file">PCB, then both sides of the circle should be based on this point. add notes.

2. The side of the printed board must retain a 5mm process (the minimum distance that the printed board needs to be printed).

https://app.roll20.net/forum/post/10907637/optical-fiducial-pcb-design-fs-technology/?pageforid=10907637#post-10907637">https://5jrorwxhjlmprik.ldycdn.com/cloud/inBqmKqjRikSrpjoniio/pcb.jpg" alt="fast turnaround pcb assembly"/>

For chips whose IC pin center distance is less than 0.65mm, the edge distance of the board surface (including processing) should be greater than 13.mm, and the four sides of the table surface should be removed with arc5 arcs. Starting from the straight rotor plane, the optimal connection length is 200mm ( Processing width: length 330mm, maximum width 250mm), try not to change the width direction to avoid bending during operation. .

3. List the rules of procedure.

Point-to-point, known as point-to-point, forms a common point for measuring parts of the countertop to ensure that each component is accurately identified in the blueprint. Therefore, the FS technology brand is considered to be an important part of https://www.zikinf.com/annonces/annonce-2061471">SMT operations.

Please refer to this section for planning information.

1) Structure: It is required to mark the thread diameter: R=1.0mm solid circle.
2) Create complete MARK articles, including featured articles (or feature articles) and open spaces.
3) Location: The entrance area should be sloped from the floor or puzzle and should be as far away as possible. It's better to put it in a remote location (for example, in the input graph).
4) In order to meet the requirements of FS technology research, SMT requires at least one MARK point on each circuit board of the SMT machine, and a card must have a MARK (when assembled).
The MARK or MARK board only plays a key role in the setup.
5) Positions related to MARK scores must be 1 at the time of appointment.
The MARK position cannot be moved for any reason, so make the MARK positions uneven for each table.
6) All MARK points on the circle are valid: Two MARK points are allowed on a diagonal line.
So, to use MARK scores, you must have a pair (MARK cards).

fast technology

https://luozhan2022.wixsite.com/website/post/optical-fiducial-pcb-design-fs-technology">https://5krorwxhjlmpiik.ldycdn.com/cloud/iqBqmKqjRikSrpjoqiio/components-sourcing.jpg" alt="light pcb assembly"/>

7) The distance between the MARK (hole bank) and the round edge should be ≥5.0mm (minimum distance from the rotating machine)

8) External requirements.

There should be a slightly open area near signs for other activities in the line.
The circle radius of the open line is R≥2R, where R is the MARK radio.
The vehicle recognition effect is good after changing to R 3R.

9) Central Bank Equipment

Symptoms can be made from antioxidants protected by pure copper. If using a welding helmet, do not cover exposed areas with exposed parts.

10) Comparison of the People's Bank of China.

A. When the local signal is significantly different from the circuit board substrate, good recognition performance can be achieved.
B. Be the same in front of all signs.
Some notes:
1) https://fspcba.livedoor.blog/archives/14357675.html">Demonstration points are used for welding and optical watermarking.

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According to the performance of the circular signal, the vehicle characteristics, vehicle grades, and local signs (called instrument grade points) are divided.
2) In the FS technique, the grinding process and the grinding edge should not freeze, there should be at least 3 L marks and the points showing the diagonal marks are not equal between the centers.
3) If the part is on both sides, write the part on both sides.
4) Write as many points as you need to collect on the https://nextsocial.net/read-blog/2190">baord. Do not mark on boards without spaces.
5) Mark on the BGA the closest QFP connected between the battery hagati ≤ 0.5 mm and 0.8 mm apart.

## Problem

A string is simply an ordered collection of symbols selected from some alphabet and formed into a word; the length of a string is the number of symbols that it contains.

An example of an DNA string (whose alphabet contains the symbols A, C, G, and T) is ATGCTTCAGAAAGGTCTTACG.

Given: A DNA string $s$ of length at most 1000 nucleotides.

Return: Four integers corresponding to the number of times that the symbols A, C, G, and T occur in $s$.

## Sample Dataset

AGCTTTTCATTCTGACTGCAACGGGCAATATGTCTCTGTGTGGATTAAAAAAAGAGTGTCTGATAGCAGC


## Sample Output

20 12 17 21