encode and decode string

Author: always-maap

36.ValidSudoku.py

@@ -53,25 +53,24 @@
 # O(n ^ 2) time | O(n) space
 class Solution:
     def isValidSudoku(self, board: List[List[str]]) -> bool:
-        row_set = defaultdict(set)
-        col_set = defaultdict(set)
-        sec_set = defaultdict(set)
+        row_dict = defaultdict(set)
+        col_dict = defaultdict(set)
+        sec_dict = defaultdict(set)
 
         for i in range(9):
             for j in range(9):
                 num = board[i][j]
 
-                if num == '.':
+                if num == ".":
                     continue
 
                 sec = (i // 3, j // 3)
 
-                if num in row_set[i] or num in col_set[j] or num in sec_set[sec]:
+                if num in row_dict[i] or num in col_dict[j] or num in sec_dict[sec]:
                     return False
                 else:
-                    row_set[i].add(num)
-                    col_set[j].add(num)
-                    sec_set[sec].add(num)
+                    row_dict[i].add(num)
+                    col_dict[j].add(num)
+                    sec_dict[sec].add(num)
 
-        print(row_set)
         return True

659.EncodeAndDecodeStrings.py

@@ -0,0 +1,48 @@
+"""
+659. Encode and Decode Strings
+Medium
+
+---
+Design an algorithm to encode a list of strings to a string.
+ The encoded string is then sent over the network and is decoded back to the original list of strings.
+
+Please implement encode and decode
+
+
+Example1
+Input: ["lint","code","love","you"]
+Output: ["lint","code","love","you"]
+Explanation:
+One possible encode method is: "lint:;code:;love:;you"
+
+Example2
+Input: ["we", "say", ":", "yes"]
+Output: ["we", "say", ":", "yes"]
+Explanation:
+One possible encode method is: "we:;say:;:::;yes"
+"""
+
+from typing import List
+
+
+class Solution:
+    # O(n) time | O(1) space
+    def encode(self, strs: List[str]):
+        res = ""
+        for s in strs:
+            res += str(len(s)) + "#" + s
+        return res
+
+    # O(n ^ 2) time | O(l) space
+    def decode(self, str: str):
+        res, i = [], 0
+
+        while i < len(str):
+            j = i
+            while str[j] != "#":
+                j += 1
+            l = int(str[i:j])
+            res.append(str[j + 1 : j + 1 + l])
+            i = j + 1 + l
+
+        return res