My Python Homeworks

Students/Hui Zhang/Session 1/CodingBat/Warmup-1/MUST --- missing_char.py

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+# Question:Given a non-empty string and an int n, return a new string where 
+# the char at index n has been removed. The value of n will be a valid index 
+# of a char in the original string (i.e. n will be in the range 0..len(str)-1 inclusive).
+#
+# See example below:
+# missing_char('kitten', 1) → 'ktten'
+# missing_char('kitten', 0) → 'itten'
+# missing_char('kitten', 4) → 'kittn'
+
+# My solution
+def missing_char(str, n):
+    strlength = len(str)
+    if n == 0:
+        str1 = str[1:strlength]
+        return str1
+    elif n == strlength:
+        str1 = str[:(strlength-1)]
+        return str1
+    else:
+        str1 = str[0:n] + str[(n+1):strlength]
+        return str1
+# End
+
+# Better solution:
+
+def missing_char(str, n):
+  front = str[:n]   # up to but not including n
+  back = str[n+1:]  # n+1 through end of string
+  return front + back
+# End

Students/Hui Zhang/Session 1/CodingBat/Warmup-1/diff21.py

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+def diff21(n):
+    if n > 21:
+        return 2*abs(21-n)
+    else:
+        return abs(21-n)
+

Students/Hui Zhang/Session 1/CodingBat/Warmup-1/front3.py

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+def front3(str):
+    if len(str) >= 3:
+        return str[:3] + str[:3] + str[:3]
+    else:
+        return str + str + str
+

Students/Hui Zhang/Session 1/CodingBat/Warmup-1/front_back.py

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+def front_back(str):
+   if len(str) == 1:
+       return(str)
+   else:
+       front = str[:1]
+       back = str[len(str)-1:]
+       middle = str[1:(len(str)-1)]
+       newstr =  back + middle + front
+       return newstr
+

Students/Hui Zhang/Session 1/CodingBat/Warmup-1/makes10.py

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+def makes10(a, b):
+    if a == 10 or b == 10 or a + b == 10:
+        return True
+    else:
+        return False
+

Students/Hui Zhang/Session 1/CodingBat/Warmup-1/monkey_trouble.py

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+def monkey_trouble(a_smile, b_smile):
+  if a_smile and b_smile:
+      return True
+  elif not a_smile and not b_smile:
+      return True
+  else:
+      return False
+

Students/Hui Zhang/Session 1/CodingBat/Warmup-1/near_hundred.py

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+def near_hundred(n):
+    if (abs(100 - n) <= 10) or (abs(200 - n) <= 10):
+        return True
+    else:
+        return False
+

Students/Hui Zhang/Session 1/CodingBat/Warmup-1/not_string.py

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+def not_string(str):
+  if str.find("not") == 0:
+      return str
+  else:
+      return "not" + " " + str

Students/Hui Zhang/Session 1/CodingBat/Warmup-1/parrot_trouble.py

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+def parrot_trouble(talking, hour):
+    if talking and (hour < 7 or hour >20):
+        return True
+    else:
+        return False
+

Students/Hui Zhang/Session 1/CodingBat/Warmup-1/pos_neg.py

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+def pos_neg(a, b, negative):
+    if (a < 0 and b > 0 and not negative) or (a > 0 and b < 0 and not negative):
+        return True
+    elif (negative and a < 0 and b < 0):
+        return True
+    else:
+        return False
+

Students/Hui Zhang/Session 1/CodingBat/Warmup-1/sleep_in.py

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+def sleep_in(weekday, vacation):
+    if not weekday or vacation:
+        return True
+    else:
+        return False
+

Students/Hui Zhang/Session 1/CodingBat/Warmup-1/sum_double.py

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+def sum_double(a, b):
+    if a == b:
+        return 2*(a + b)
+    else:
+        return a + b
+

Students/Hui Zhang/Session 1/CodingBat/Warmup-2/MUST --- Wrong --- arrary123.py~

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+def array123(nums):
+    n = len(nums)
+    if n < 3:
+        return(False)
+    elif n == 3:
+        if nums[0] == 1 and nums[1] == 2 and nums[2] == 3:
+            return(True)
+        else:
+            return(False) 
+    elif n > 3:
+        count1 = 0
+        for i in range(0,n-2):
+            if (nums[i] == 1) and (nums[i+1] == 2) and (nums[i+2] == 3):
+                count1 = count1 + 1
+        if count1 >= 1:
+            return(True)
+        else:
+            return(False)

Students/Hui Zhang/Session 1/CodingBat/Warmup-2/MUST --- Wrong --- last2.py~

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+def last2(str):
+    str1 = str[-2:]
+    n = str.count(str1) -1
+    return(n)

Students/Hui Zhang/Session 1/CodingBat/Warmup-2/MUST --- arrary123.py

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+def array123(nums):
+    n = len(nums)
+    if n < 3:
+        return(False)
+    elif n == 3:
+        if nums[0] == 1 and nums[1] == 2 and nums[2] == 3:
+            return(True)
+        else:
+            return(False) 
+    elif n > 3:
+        count1 = 0
+        for i in range(0,n-2):
+            if (nums[i] == 1) and (nums[i+1] == 2) and (nums[i+2] == 3):
+                count1 = count1 + 1
+        if count1 >= 1:
+            return(True)
+        else:
+            return(False)

Students/Hui Zhang/Session 1/CodingBat/Warmup-2/MUST --- array_count9.py

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+def array_count9(nums):
+    count1 = 0
+    for i in range(len(nums)):
+        if 9 - nums[i] == 0:
+            count1 = count1 + 1
+    return(count1)
+

Students/Hui Zhang/Session 1/CodingBat/Warmup-2/MUST --- array_front9.py

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+def array_front9(nums):
+    n = len(nums)
+    count1 = 0
+    if n >= 4:
+        for i in range(4):
+            if 9 - nums[i] == 0:
+                count1 = count1 + 1
+        if count1 >= 1:
+            return(True)
+        else:
+            return(False)
+    else:
+        for i in range(n):
+            if 9 - nums[i] == 0:
+                count1 = count1 + 1
+        if count1 >= 1:
+            return(True)
+        else:
+            return(False)

Students/Hui Zhang/Session 1/CodingBat/Warmup-2/MUST --- last2.py

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+def last2(str):
+    str1 = str[-2:]
+    n = len(str) 
+    count1 = 0
+    for i in range(n-1):
+        # only check substring with length 2 from far left to two to far right in the string. 
+        if i+2 <= n-1: 
+            if str[i:(i+2)] == str1:
+                count1 = count1 + 1
+    return(count1)

Students/Hui Zhang/Session 1/CodingBat/Warmup-2/MUST --- string_bits.py

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+def string_bits(str):
+    strlength = len(str)
+    newstr = ''
+    for i in range(1,strlength+1,2):
+      newstr = newstr + str[(i-1):i]
+    return(newstr)

Students/Hui Zhang/Session 1/CodingBat/Warmup-2/MUST --- string_match.py

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+def string_match(a, b):
+  count1 = 0
+  n = max(len(a),len(b))
+  for i in range(n-1):
+       if i+1 <= len(a) and i+1 <= len(b):
+           if a[i:(i+2)] == b[i:(i+2)]: 
+              count1 = count1 + 1
+  return(count1)
+

Students/Hui Zhang/Session 1/CodingBat/Warmup-2/MUST --- string_splosion.py

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+def string_splosion(str):
+    newstr = str
+    newstr2 = str
+    strlength = len(str)
+    for i in range(1,strlength+1):
+        newstr1 = newstr[:(strlength - i)]
+        newstr2 = newstr1+ newstr2
+    return(newstr2)
+

Students/Hui Zhang/Session 1/CodingBat/Warmup-2/array123-test.py~

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+def array123(nums):
+    print nums
+    n = len(nums)
+    print n
+    count1 = 0
+    for i in range(0,3):
+        if (nums[i] == 1) and (nums[i+1] == 2) and (nums[i+2] == 3):
+            print i
+            print nums[i], nums[i+1], nums[i+2]
+            count1 = count1 + 1
+        if count1 >= 1:
+           print count1
+           return(True)
+        else:
+           print count1
+           return(True)
+
+array123([1, 1, 2, 3, 1])
+
+

Students/Hui Zhang/Session 1/CodingBat/Warmup-2/front_times.py

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+def front_times(str, n):
+  if len(str) >= 3:
+      return(n*str[:3])
+  else:
+      return(n*str)

Students/Hui Zhang/Session 1/CodingBat/Warmup-2/string_times.py

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+def string_times(str, n):
+    return(n*str)
+

Students/Hui Zhang/Session 1/break_me.py

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+-------------
+-------------
+Create a funtcion to trigger AttributeError
+
+def testatterror():
+    n = 5
+    n.append(4)
+    print n
+   .....:     
+
+In [104]: testatterror()
+---------------------------------------------------------------------------
+AttributeError                            Traceback (most recent call last)
+<ipython-input-104-e6cab665e2fa> in <module>()
+----> 1 testatterror()
+
+<ipython-input-103-d6290a627534> in testatterror()
+      1 def testatterror():
+      2     n = 5
+----> 3     n.append(4)
+      4     print n
+      5 
+
+AttributeError: 'int' object has no attribute 'append'
+
+In [105]: 
+
+
+
+
+-------------
+-------------
+Create a funtcion to trigger TypeError
+
+
+def testtypeerror():
+    n = '5'
+    m =  5
+    mn = m + n
+    print mn
+   ....:     
+
+In [99]: testtypeerror()
+---------------------------------------------------------------------------
+TypeError                                 Traceback (most recent call last)
+<ipython-input-99-2c3a32be449d> in <module>()
+----> 1 testtypeerror()
+
+<ipython-input-98-dc82486ac12c> in testtypeerror()
+      7     n = '5'
+      8     m =  5
+----> 9     mn = m + n
+     10     print mn
+     11 
+
+TypeError: unsupported operand type(s) for +: 'int' and 'str'
+
+In [100]: 
+
+
+
+
+-------------
+-------------
+Create a funtcion to trigger NameError
+def testnameerror():
+    print nn
+
+
+In [89]: testnameerror()
+---------------------------------------------------------------------------
+NameError                                 Traceback (most recent call last)
+<ipython-input-89-23be1ea02b92> in <module>()
+----> 1 testnameerror()
+
+<ipython-input-88-e54aba5a1687> in testnameerror()
+      1 def testnameerror():
+----> 2     print nn
+      3 
+
+NameError: global name 'nn' is not defined
+
+
+
+
+-------------
+-------------
+Create a function to trigger SyntaxError
+
+def testnameerror()
+    print n
+
+In [85]: def testnameerror()
+  File "<ipython-input-85-0ef4b784a7a2>", line 1
+    def testnameerror()
+                       ^
+SyntaxError: invalid syntax
+

Students/Hui Zhang/Session 1/fungrid-p1.py

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+# my fungrid 
+def fungrid():
+    for i in range(0, 2):
+        print'+ - - - - + - - - - +'
+        for n in range(0, 4):
+            print'|         |         |'
+    print'+ - - - - + - - - - +'
+fungrid()

Students/Hui Zhang/Session 1/fungrid-p2.py

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+# my fungrid 
+n = input('Please input your number:' )
+def fungrid():
+    for i in range(0, 2):
+        print '+' + n*'-' + '+' + n*'-' + '+'
+        for m in range(0, n):
+            print '|' + n*' ' + '|' + n*' ' + '|'
+    print '+' + n*'-' + '+' + n*'-' + '+'
+fungrid()

Students/Hui Zhang/Session 1/fungrid-p3.py

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+# my fungrid
+n = input('Please input your number:' )
+def fungrid():
+    for i in range(0, 3):
+        print '+' + n*'-' + '+' + n*'-' + '+' + n*'-' + '+'
+        for m in range(0, n):
+            print '|' + n*' ' + '|' + n*' ' + '|' + n*' ' + '|'
+    print '+' + n*'-' + '+' + n*'-' + '+' + n*'-' + '+'
+fungrid()

Students/Hui Zhang/Session 1/fungrid.py

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+# my fungrid 
+def fungrid():
+    for i in range(0, 2):
+        print'+ - - - - + - - - - +'
+        for n in range(0, 4):
+            print'|         |         |'
+    print'+ - - - - + - - - - +'
+fungrid()