Longest Consecutive Sequence

Author: thispath98

longest-common-subsequence/thispath98.py

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+"""
+# Time Complexity: O(N)
+- lce_dict 생성: N
+- N개의 key에 대하여 순회하면서 값 확인: N
+# Space Compelexity: O(k)
+- 중복되지 않은 key k개 저장
+"""
+class Solution:
+    def longestConsecutive(self, nums: List[int]) -> int:
+        if not nums:
+            return 0
+
+        lce_dict = {}
+        for num in nums:
+            lce_dict[num] = True
+
+        answer = 0
+        for num in nums:
+            cur_lce = 1
+            if lce_dict.pop(num, None) is None:
+                continue
+
+            down_num = num - 1
+            while down_num in lce_dict:
+                cur_lce += 1
+                lce_dict.pop(down_num)
+                down_num -= 1
+                
+            up_num = num + 1
+            while up_num in lce_dict:
+                cur_lce += 1
+                lce_dict.pop(up_num)
+                up_num += 1
+
+            answer = answer if answer > cur_lce else cur_lce
+
+        return answer