Find Minimum in Rotated Sorted Array

arai60/find-minimum-in-rotated-sorted-array/step1.py

@@ -0,0 +1,19 @@
+"""
+5m30s
+前やったのとほぼ同じ
+"""
+
+class Solution:
+    def findMin(self, nums: List[int]) -> int:
+        if nums == sorted(nums):
+            return nums[0]
+
+        left = 0
+        right = len(nums) - 1
+        while right - left > 1:
+            mid = (left + right) // 2
+            if nums[left] <= nums[mid]:
+                left = mid
+            else:
+                right = mid
+        return nums[right]

arai60/find-minimum-in-rotated-sorted-array/step2.py

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+"""
+わざわざソートしなくても比較するだけでよい
+"""
+
+class Solution:
+    def findMin(self, nums: List[int]) -> int:
+        if nums[0] <= nums[-1]:
+            return nums[0]
+
+        left = 0
+        right = len(nums) - 1
+        while right - left > 1:
+            mid = (left + right) // 2
+            if nums[left] <= nums[mid]:
+                left = mid
+            else:
+                right = mid
+        return nums[right]
+
+# 固定値と比較して寄せていくパターン
+# これならソートされていても動く
+class Solution:
+    def findMin(self, nums: List[int]) -> int:
+        left = -1
+        right = len(nums) - 1
+        while right - left > 1:
+            mid = (left + right) // 2
+            if nums[mid] >= nums[-1]:
+                left = mid
+            else:
+                right = mid
+        return nums[right]
+
+# leftをmidより動かすパターン
+# 最小値を直接あてに行く
+class Solution:
+    def findMin(self, nums: List[int]) -> int:
+        left = 0
+        right = len(nums) - 1
+        while left < right:
+            mid = (left + right) // 2
+            if nums[mid] <= nums[-1]:
+                right = mid
+            else:
+                left = mid + 1
+        return nums[left]