Add 581

Author: trung-hn

Readme.md

@@ -150,6 +150,7 @@
 | 563 | Binary Tree Tilt | Easy | O(N) | O(H) | Tree, DFS, Recursion | | |
 | 567 | Permutation in String | Medium | O(S1 + S2) | O(1) | String, Two Pointers, Sliding Window | | |
 | 573 | Squirrel Simulation | Medium | O(N) | O(1) | Premium, Math | | 🔒 |
+| 581 | Shortest Unsorted Continuous Subarray | Medium | O(N) | O(1) | Array | | |
 | 583 | Delete Operation for Two Strings | Medium | O(N^2) | O(N) | Dynamic Programming, String | | |
 | 593 | Valid Square | Medium | O(1) | O(1) | Math | | |
 | 605 | Can Place Flowers | Easy | O(N) | O(1) | Array, Greedy | | |

src/581.shortest-unsorted-continuous-subarray.py

@@ -0,0 +1,45 @@
+#
+# @lc app=leetcode id=581 lang=python3
+#
+# [581] Shortest Unsorted Continuous Subarray
+#
+
+# @lc code=start
+# TAGS: Array
+class Solution:
+    # 216 ms, 83 %. O(NlogN)
+    def findUnsortedSubarray(self, nums: List[int]) -> int:
+        sorted_nums = sorted(nums)
+        start = end = -1
+        for i in range(len(nums)):
+            if nums[i] != sorted_nums[i]:
+                if start == -1:
+                    start = i
+                end = i
+        return 0 if start == end == -1 else end - start + 1
+    
+    # 196 ms, 81.96%. Time: O(N). Space: O(1)
+    def findUnsortedSubarray(self, nums: List[int]) -> int:
+        # Find right limit of the subarray. Traverse array from left to right
+        right_ptr = 0
+        big = nums[0]
+        for i in range(len(nums)):
+            if nums[i] < big:
+                right_ptr = i
+            else:
+                big = nums[i]
+        
+        # Find left limit of the subarray.Traverse array from right to left
+        left_ptr = 0
+        small = nums[-1]
+        for i in reversed(range(len(nums))):
+            if nums[i] > small:
+                left_ptr = i
+            else:
+                small = nums[i]
+                
+        if right_ptr == left_ptr: return 0
+        return right_ptr - left_ptr + 1
+    
+# @lc code=end
+