# Review
### robert1003 @ Py2021
----
## 要複習什麼呢？
* [basic](https://drive.google.com/file/d/1qZXuZUS0R26UTzTdPR-PoSkQOLZoK7ZK/view)
* [if-elif-else](https://drive.google.com/file/d/1GgiB09kKqbP1Aw-ojfJ4peK-RHIcTL6z/view)
* [while](https://drive.google.com/file/d/1neF7Gb7O50aWHhmukCUh33KKTN6xebFy/view)
* [for](https://drive.google.com/file/d/1a91AcD1h3cqO4VvQpNMp0S8QRDxkYtuP/view)
* [list](https://drive.google.com/file/d/1EEsrCvpSB2asnNRey3EqJBsJxDsm_e_2/view)
* [string](https://drive.google.com/file/d/1UGQYHhbCMau4bRLEoF6Mv1Xt2-uybmGW/view)
* [dictionary](https://drive.google.com/file/d/1M9lhUEPVSV12OP_Z0Hkh9ijjO-2kgAbD/view)
* [function](https://drive.google.com/file/d/1Pmy3uqwWaav5MUNoonH8Vfs4hzYFaek1/view)
* [import](https://drive.google.com/file/d/1rBZs-HSJ0-Km_3Zoi4NHlVne_56o3rIE/view)
---
## Basic
```python=
# 變數
a = 3
# 型態：str, int, bool, float, list, dict, NoneType, type
# 檢查型態：type()
print(type(a), type("a"), type(1.2), type([]), type(None))
# 轉型
b = str(a)
print(b, type(b))
```
----
## 輸入、輸出、跳脫字元
```python=
# 輸入
s = input()
print(type(s)) # str type
# 輸出：間隔、結尾
print("a", "b", sep=' ya ', end=' yaya ')
# 跳脫字元
s = "a\nb"
print(s)
p = "a\\nb"
print(p)
```
----
## 運算子
```python=
# int, float: +, -, *, /, //, **, %
print(3+2, 3-2, 3*2, 3/2, 3//2, 3**2, 3%2)
# str: +, *
print('a'+'b', 'a'*10)
# assign: +=, -=, ...
a = 1
a += 2
print(a)
```
---
## if-elif-else
```python=
# 關係運算：>, <, ==, !=, >=, <=
print(3>2, 3<2, 3==2, 3!=2, 3>=2, 3<=2)
# 邏輯運算 -> 產生 bool expression:
c1 = (3 > 2)
c2 = (3 < 2)
print(c1 and c2, c1 or c2, not c1)
```
----
## prototype
```python=
if expression:
statement(s)
elif expression2:
statement(s)
else:
statement(s)
```
----
## 分數轉換成等第
```python=
score = int(input())
if score < 60:
print('F')
elif score < 80:
print('C')
elif score < 90:
print('B'):
else:
print('A')
```
---
## while
```python=
while expression:
statement(s)
if expression:
continue # 跳過這次回圈（剩下的 code）
if expression:
break # 跳出 while
```
----
## 判斷質數
```python=
n = int(input())
i = 2
prime = True
while i < n:
if n % i == 0:
prime = False
break
i += 1
print(prime)
```
----
## 讓程式碼跳舞？
```python=
i = 0
while i < 10:
if i == 5:
continue
print(i)
```
---
## for
```python=
# iterable: list, dict, range, string...
# range(start, stop, step), 左閉右開
for [variable] in [iterable]:
statement(s)
```
----
## 印出 9x9 乘法表
```python=
for i in range(1, 10):
for j in range(1, 10):
print(i, 'x', j, '=', i*j, sep='', end=' ')
print()
```
----
## 遍歷 list
```python=
for prime in [2, 3, 5, 7, 11]:
print(prime)
```
---
## list
```python=
# list 可以放任何 type 的東西，包括 list
a = [1, 2, '3', 4.5, [6, 7, 8]]
# 長度？
print(len(a))
# 取值，改值: 0 <= idx < len(a), -len(a) <= idx <= -1
print(a[0], a[-1])
a[0], a[-1] = 1, 2
print(a[0], a[-1])
```
----
## list part 2
```python=
# 遍歷: i=index, v=value
for i, v in enumerate(a):
print(i, v)
# function: min, max, sum
a = [1, 2, 3]
print(min(a), max(a), sum(a))
# Method
a.append(4)
a.pop()
a.index(3)
a.clear()
```
----
## list part 3
```python=
# slicing
b = a[start : stop : step]
# copy
b = a[:]
# map
a = list(map(int, input().split()))
print(a)
```
---
## dictionary
```python=
# 建立 dictionary
d = {1:2, 2:3, '3':4} # {key: value...}
# 長度（個數）
print(len(d))
# 取值
print(d[1], d['3'])
print(d[3]) # key 不在裡面會爛掉
# 檢查 key
print(3 in d, '3' in d)
# 新增＆修改
d[3] = 4
d['3'] = 123
print(d[3], d['3'])
```
----
## dictionary part 2
```python=
# 遍歷
for k, v in d.items():
print(k, v)
# 刪除某個 (key, value)
d.pop(3)
# 清空
d.clear()
```
---
## string
* Immutable
```python=
# 建立: 雙引單引都可以
print('123', "123")
# 比大小：字典序
s, p = 'abcb', 'abdb'
print(s > p)
# 函數
# 取代
print(s.replace('b', 'd')) # s.replace(字串串, 新字串)
# 去頭尾
print(' 123 '.strip()) # s.strip(要去除的字元們) 預設空白
# 分割
print(s.split('bc')) # s.split(sep字串串)
# 搜尋
print(s.find('bc')) # s.find(要找的字串串, 開始=0, end=無限大), 找不到回傳 -1
# 結合
print(','.join(['a', 'b', 'c'])) # 結合字元.join(list of str)
```
----
## （補充）印出漂亮 9x9 乘法表
```python=
for i in range(1, 10):
for j in range(1, 10):
print('{:1}x{:1}={:2}'.format(i, j, i*j), end=' ')
print()
```
---
## function
```python=
def 函數名稱(變數1, 變數2, 變數3=預設值):
statement(s)
return 結果
```
----
## 簡單ㄉ例子
```python=
def f(a, b, c=1, d=2):
s = a + b + c
p = a + b + c + d
return s, p
r1, r2 = f(1, 2, 3, 4)
print(r1, r2)
print(f(1, 2, d=3))
```
---
## import
```python=
# 好多種 import 的方式
import math
import math as m
from math import gcd
from math import gcd as ggggggcd
print(math.gcd(4, 6))
print(m.gcd(4, 6))
print(gcd(4, 6))
print(ggggggcd(4, 6))
```
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