upload solutions to 136. Single Number

uzzielkyle · uzzielkyle · commit eba5782a9a83 · 2023-10-18T17:32:57.000+08:00
diff --git a/136.single-number.py b/136.single-number.py
@@ -0,0 +1,87 @@
+# EASY
+
+# first submission
+# runtime: 129 ms O(n)
+# memory: 19 MB 
+class Solution:
+    def singleNumber(self, nums: list[int]) -> int:
+        dict = {}
+        for num in nums:
+            if num in dict.keys():
+                dict.pop(num)
+                continue
+
+            dict[num] = 1
+
+        return dict.popitem()[0]
+    
+    
+# second submission
+# runtime: 124 ms O(n)
+# memory: 18.8 MB 
+# src: https://medium.com/@punitkmr/single-number-fe30e4f6693d
+class Solution:
+    def singleNumber(self, nums: list[int]) -> int:
+        dict = {}
+        for num in nums:
+            try:
+                dict.pop(num)
+            except:
+                dict[num] = 1
+
+        return dict.popitem()[0]
+    
+    
+# third submission
+# runtime: 128 ms O(n)
+# memory: 19 MB 
+# src: https://medium.com/@punitkmr/single-number-fe30e4f6693d
+class Solution:
+    def singleNumber(self, nums: list[int]) -> int:
+        return (2 * sum(set(nums))) - sum(nums)
+    
+    
+# fourth submission
+# runtime: 771 ms O(n^2)
+# memory: 19.1 MB 
+class Solution:
+    def singleNumber(self, nums: list[int]) -> int:
+        numlist = []
+        for num in nums:
+            if num in numlist:
+                numlist.remove(num)
+                continue
+
+            numlist.append(num)
+
+        return numlist[0]
+    
+    
+# fifth submission
+# runtime: 128 ms O(n)
+# memory: 18.8 MB 
+# src: https://medium.com/@punitkmr/single-number-fe30e4f6693d
+class Solution:
+    def singleNumber(self, nums: list[int]) -> int:
+        single_num = 0
+        for num in nums:
+            single_num ^= num
+
+        return single_num 
+    
+    
+# sixth submission
+# runtime: 137 ms O(n)
+# memory: 18.6 MB 
+# src: https://dzone.com/articles/optimal-solution-single-number-leetcode-problem
+class Solution:
+    def singleNumber(self, nums: list[int]) -> int:
+        nums.sort()
+        idx = 0
+        while idx < len(nums) - 2:
+            if nums[idx] != nums[idx + 1]:
+                return nums[idx]
+
+            idx += 2
+
+        return nums[idx]
