added Single Number 2 (medium)

Author: minhyeong-joe

Hard/EscapeLargeMaze/solution.py

@@ -9,8 +9,8 @@ def isEscapePossible(self, blocked: List[List[int]], source: List[int], target:
  visited = set()
  queue.append(source)
  while queue:
- print("queue:", queue)
- print("visited:", visited)
+ # print("queue:", queue)
+ # print("visited:", visited)
  currentCoord = queue.pop(0)
  if currentCoord == target:
  return True
@@ -30,7 +30,7 @@ def isEscapePossible(self, blocked: List[List[int]], source: List[int], target:
 
 # test driver
 sol = Solution()
-blocked = [[1,2], [0,2], [2,2]]
+blocked = []
 source = [0,0]
-target = [3,3]
+target = [9, 9]
 print("Output:", sol.isEscapePossible(blocked, source, target))

Medium/SingleNumber2/README.md

@@ -0,0 +1,20 @@
+
+# Single Number II
+[Leetcode Link](https://leetcode.com/problems/single-number-ii/)
+
+## Problem:
+
+Given a **non-empty** array of integers, every element appears three times except for one, which appears exactly once. Find that single one.
+
+Your algorithm should have a linear runtime complexity. Could you implement it without using extra memory?
+
+## Example:
+
+```
+Input: [2,2,3,2]
+Output: 3
+```
+```
+Input: [0,1,0,1,0,1,99]
+Output: 99
+```

Medium/SingleNumber2/solution.py

@@ -0,0 +1,31 @@
+from typing import List
+
+class Solution:
+ def singleNumber(self, nums: List[int]) -> int:
+ binSum = 0
+ mask = bin((1<<32) -1)
+ uniqueBin = ""
+ for num in nums:
+ binary = int(bin(num & int(mask,2))[2:])
+ print(num, "=", binary)
+ binSum += binary
+ print("sum =", binSum)
+ for bit in str(binSum):
+ if int(bit) % 3 != 0:
+ uniqueBin += "1"
+ else:
+ uniqueBin += "0"
+ print("unique number in binary:", uniqueBin)
+ if int(uniqueBin, 2) > 2**31:
+ uniqueBin = str(bin(int(uniqueBin,2)-1))
+ print(uniqueBin)
+ print(bin((~int(uniqueBin, 2) & int(mask,2))))
+ return -(~int(uniqueBin, 2) & int(mask,2))
+ return int(uniqueBin, 2)
+ 
+
+# test driver
+sol = Solution()
+input = [-19,-46,-19,-46,-9,-9,-19,17,17,17,-13,-13,-9,-13,-46,-28]
+print("Input:", input)
+print("Output:", sol.singleNumber(input))

README.md

@@ -78,6 +78,7 @@ Languages used: Java and Python
  - [Number of Operations to Make Network Connected](Medium/NumToMakeNetworkConnected)
  - [Sort Colors](Medium/SortColors)
  - [Design Linked List](Medium/DesignLinkedList)
+ - [Single Number II](Medium/SingleNumber2)
 - Hard
  - [Maximum Score Words Formed by Letters](Hard/MaximumScoreWords)
  - [Reducing Dishes](Hard/ReducingDishes)