#!/usr/bin/env python
# coding: utf-8

# # Hàm

# ## Định nghĩa hàm

# In[1]:


def is_even(i):
    """
    Input: i, a positive int
    Returns True if i is even, otherwise False
    """
    print("hi")
    return i % 2 == 0

is_even(3)


# ### Bài tập
# 
# Write a function isIn that accepts two strings as arguments and returns True if either string occurs anywhere in the other, and False otherwise. Hint: you might want to use the built-in str operation in.

# ## Phạm vi của biến

# In[3]:


def f( x ):
    x = x + 1
    print('in f(x): x =', x)
    return x

x = 3
z = f( x )
print('out f(x): x =', x)


# In[2]:


def is_even( i ):
    i % 2 == 0
    
a = is_even(3)
type(a)


# In[11]:


def func_a():
    print('inside func_a')
def func_b(y):
    print('inside func_b')
    return y
def func_c(z):
    print('inside func_c')
    return z()

print(func_a())
print(5 + func_b(2))
print(func_c(func_a))


# In[12]:


def f(y):
    x = 1
    x += 1
    print(x)

x = 5
f(x)
print(x)


# In[13]:


def g(y):
    print(x)
    print(x + 1)
    
x = 5
g(x)
print(x)


# In[14]:


def h(y):
    x = x + 1
    
x = 5
h(x)
print(x)


# In[16]:


def g(x):
    def h():
        x = 'abc'
    x = x + 1
    print('in g(x): x =', x)
    h()
    return x

x = 3
z = g(x)
z


# ## Tham số đặt tên - Keyword Arguments

# In[19]:


def printName(firstName, lastName, reverse):
    if reverse:
        print(lastName + ', ' + firstName)
    else:
        print(firstName, lastName)
        
printName('Eric', 'Grimson', False)

printName('Eric', 'Grimson', reverse = False)

printName('Eric', lastName = 'Grimson', reverse = False)

printName(lastName = 'Grimson', firstName = 'Eric', reverse = False)


# ## Giá trị mặc định - default values

# In[20]:


def printName(firstName, lastName, reverse = False):
    if reverse:
        print(lastName + ', ' + firstName)
    else:
        print(firstName, lastName)
        
printName('Eric', 'Grimson')

printName('Eric', 'Grimson', True)


# ## Các đặt tả - specification/docstring

# In[24]:


def is_even( i ):
    """
    Input: i, a positive int
    Returns True if i is even, otherwise False
    """
    print('hi')
    return i % 2 == 0

# hit Shift-Tab to see docstring
is_even(3)


# ## Đệ qui

# In[47]:


def mult_iter(a, b):
    result = 0
    while b > 0:
        result += a
        b -= 1
    return result
    
mult_iter(2, 3)


# In[48]:


def mult(a, b):
    if b == 1:
        return a
    else:
        return a + mult(a, b-1)
    
mult(2, 3)


# In[49]:


def fact(n):
    if n == 1:
        return 1
    else:
        return n*fact(n-1)
    
fact(4)


# ## Towers of Hanoi
# 
# [Video giới thiệu](https://youtu.be/rVPuzFYlfYE?t=1m20s)

# In[53]:


def printMove(fr, to):
    print('move from ' + str(fr) + ' to ' + str(to))
    
def Towers(n, fr, to, spare):
    if n == 1:
        printMove(fr, to)
    else:
        Towers(n - 1, fr, spare, to)
        Towers(1, fr, to, spare)
        Towers(n - 1, spare, to, fr)
        
Towers(4, 'P1', 'P2', 'P3')


# ## Đệ qui với nhiều trường hợp ngừng (base cases)

# In[43]:


def fib(x):
    """
    assumes x an int >= 0
    return Fibonacci of x
    """
    if x == 0 or x == 1:
        return 1
    else:
        return fib(x - 1) + fib(x - 2)
    
def testFib(n):
    for i in range(n + 1):
        print('fib of', i, '=', fib(i))
        
testFib(10)


# ### Bài tập
# 
# When the implementation of fib in the above program is used to compute fib(5), how many times does it compute the value of fib(2) on the way to computing fib(5)?

#  ## Đệ qui với phi số

# In[44]:


def isPalindrome(s):
    def toChars(s):
        s = s.lower()
        ans = ''
        for c in s:
            if c in 'abcdefghijklmnopqrstuvwxyz':
                ans = ans + c
        return ans
    
    def isPal(s):
        if len(s) <= 1:
            return True
        else:
            return s[0] == s[-1] and isPal(s[1:-1])
        
    return isPal(toChars(s))

def testIsPalindrome():
    print('Try dogGod')
    print(isPalindrome('dogGod'))
    print('Try Able was I, ere I saw Elba')
    print(isPalindrome("Able was I, ere I saw Elba"))
    
testIsPalindrome()


# ## Tập tin

# In[30]:


# %load Files/circle.py
pi = 3.14159

def area(radius):
    return pi * (radius**2)

def circumference(radius):
    return 2*pi*radius


# In[2]:


from Files import circle
pi = 3
print(pi)
print(circle.pi)
print(circle.area(3))
print(circle.circumference(3))


# In[39]:


nameHandle = open('Files/kids', 'w')
for i in range(2):
    name = input('Enter name: ')
    nameHandle.write(name + '\n')
nameHandle.close()


# In[40]:


nameHandle = open('Files/kids', 'r')
for line in nameHandle:
    print(line)
nameHandle.close()


# - - -
# [Trước: Các phương pháp cơ bản giải quyết bài toán trên máy tính](http://nbviewer.jupyter.org/github/manleviet/introCSusingPython/blob/master/3%20-%20C%C3%A1c%20ph%C6%B0%C6%A1ng%20ph%C3%A1p%20c%C6%A1%20b%E1%BA%A3n%20gi%E1%BA%A3i%20quy%E1%BA%BFt%20b%C3%A0i%20to%C3%A1n%20tr%C3%AAn%20m%C3%A1y%20t%C3%ADnh.ipynb) | 
# [Mục lục](http://nbviewer.jupyter.org/github/manleviet/introCSusingPython/blob/master/index.ipynb) | 
# [Tiếp: Tuple và List](http://nbviewer.jupyter.org/github/manleviet/introCSusingPython/blob/master/5%20-%20Tuple%2C%20List.ipynb)