Huffman

src/7/file.txt

@@ -0,0 +1 @@
+enkldznczlknzdknvdkvndzvldkznvkzldvklzkndvzkdv zdm,vzssdvdvSaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa

src/7/huffman.py

@@ -0,0 +1,123 @@
+class Node:
+    def __init__(self, char, weight, left=None, right=None):
+        self.char = char
+        self.weight = weight
+        self.left = left
+        self.right = right
+
+    def __lt__(self, other):
+        return other.weight > self.weight
+
+    def getCode(self, char, parentPath):
+        if self.char == char:
+            return parentPath
+
+        if self.left:
+            left_path = self.left.getCode(char, parentPath + "0")
+            if left_path:
+                return left_path
+
+        if self.right:
+            right_path = self.right.getCode(char, parentPath + "1")
+            if right_path:
+                return right_path
+
+
+        return None
+
+
+
+def countTable(msg: str) -> dict[str, int]:
+    dict_table = {}
+    for char in msg:
+        if char in dict_table:
+            dict_table[char] += 1
+        else:
+            dict_table[char] = 1
+
+    return dict_table
+
+def huffman(nodes: list[Node]) -> Node:
+    while len(nodes) > 1:
+        nodes.sort()
+
+        left = nodes.pop(0)
+        right = nodes.pop(0)
+
+        parent = Node(None, left.weight + right.weight, left, right)
+
+        nodes.append(parent)
+
+    return nodes[0]
+
+def encode(msg: str) -> tuple[str, dict[str, str]]:
+    count_table = countTable(msg)
+
+    nodes = []
+
+    for char, weight in count_table.items():
+        nodes.append(Node(char, weight))
+
+    no = huffman(nodes)
+
+    code_table = {}
+    for i in count_table.keys():
+        code_table[i] = no.getCode(i, "")
+
+    encoded_msg = ""
+
+    for i in msg:
+        encoded_msg += code_table[i]
+
+    return encoded_msg, code_table
+
+def decode(encoded: str, table: dict[str, str]) -> str:
+    left = 0
+    values = table.values()
+
+    decoded_msg = ""
+
+    for i in range(len(encoded)):
+        cur = encoded[left:i+1]
+        for key, values in table.items():
+            if values == cur:
+                decoded_msg += key
+                left = i + 1
+                break
+
+    return decoded_msg
+
+
+def encode_file(filepath):
+    with open(filepath, "r") as f_read:
+        content = f_read.read()
+        encoded_str, table = encode(content)
+        with open("encoded.huff", "w") as f_write:
+            f_write.write(f'{len(table)}\n')
+            for key, values in table.items():
+                f_write.write(key + ":" + values + "\n")
+            f_write.write(encoded_str)
+
+
+def decode_file(filepath):
+    with open(filepath, "r") as f_read:
+        ln = f_read.readline()
+        table = {}
+        for _ in range(int(ln)):
+            line = f_read.readline()
+            key, value = line.split(":")
+            table[key] = value[0:len(value) - 1]
+        content = f_read.read()
+        decoded_str = decode(content, table)
+        with open("decoded.txt", "w") as f:
+            f.write(decoded_str)
+
+string, table = encode("Hello fsdfdfsdfsdfsdfsdfsdfsdfdsfsdfdsfWorld")
+
+decoded_string = decode(string, table)
+print(decoded_string)
+
+
+encode_file("file.txt")
+decode_file("encoded.huff")
+