18

Author: JavaProgrammerLB

18-1.py

@@ -3,7 +3,8 @@
 
 def main():
     left, right = first_step()
-    second_step(left, right)
+    diff = second_step(left, right)
+    third_step(diff)
 
 
 def first_step():
@@ -22,7 +23,34 @@ def first_step():
 
 
 def second_step(left, right):
-    pass
+    diff = difflib.ndiff(left.splitlines(keepends=True), right.splitlines(keepends=True))
+    result = "".join(diff)
+    return result
+
+
+def third_step(diff):
+    plus = open("swan/plus.png", "wb")
+    subtraction = open("swan/subtraction.png", "wb")
+    space = open("swan/space.png", "wb")
+    lines = diff.split("\n")
+    for line in lines:
+        if len(line) > 0:
+            first_byte = line[0]
+            if first_byte == "+":
+                write_file(plus, line)
+            elif first_byte == "-":
+                write_file(subtraction, line)
+            elif first_byte == " ":
+                write_file(space, line)
+
+
+def write_file(file, strings):
+    sub_strings = strings[2:]
+    ary = sub_strings.split(" ")
+    for point in ary:
+        if point.isalnum():
+            b = bytes.fromhex(point)
+            file.write(b)
 
 
 if __name__ == "__main__":

18.py

@@ -2,11 +2,21 @@
 Solve Problems in http://www.pythonchallenge.com
 
 #### 18
+```python
+import difflib
+```
 - the obvious different between two picture is brightness.
 
 ```shell
 gunzip deltas.gz
 ```
+- png file start with: 0x89 0x50 0x4E 0x47 0x0D 0x0A 0x1A 0x0A
+- 0x89 is png's magic number,all jpg file start with 0xFF
+- 0x50 decode in utf-8 is P, 0x4E for N, 0x47 for G
+- use three tag "+", "-", " " to describe the difference between two files
+> when you say a php file, there is some function in it
+- Loop: http://www.pythonchallenge.com/pc/def/linkedlist.php
+- RPC: http://www.pythonchallenge.com/pc/phonebook.php
 
 #### 17
 result: http://www.pythonchallenge.com/pc/return/balloons.html

README.md

@@ -1,5 +1,5 @@
-def main():
-    file = open("swan/plus.png", "rb")
+def read_bin_file():
+    file = open("evil/0.jpg", "rb")
     bs = []
     while True:
         b = file.read()
@@ -11,4 +11,4 @@ def main():
 
 
 if __name__ == "__main__":
-    main()
+    read_bin_file()