Binary Search 2

min_in_sorted_array.py

@@ -0,0 +1,19 @@
+# Find minimum in a rotated sorted array
+# This code uses binary search to find the minimum element in a rotated sorted array.
+class Solution(object):
+    def findMin(self, nums):
+        """
+        :type nums: List[int]
+        :rtype: int
+        """
+        l,h = 0,len(nums)-1
+        while l<=h:
+            mid = (l+h)//2
+            if nums[l]<=nums[h]:
+                return nums[l]
+            elif nums[mid]<nums[mid-1] and nums[mid]<nums[mid+1]:
+                return nums[mid]
+            elif nums[l]<=nums[mid]:
+                l = mid+1
+            else:
+                h = mid-1

peak_element.py

@@ -0,0 +1,20 @@
+# Find peak element in an array
+# This code uses binary search to find a peak element in an array
+class Solution(object):
+    def findPeakElement(self, nums):
+        """
+        :type nums: List[int]
+        :rtype: int
+        """
+        l,h = 0, len(nums)-1
+        while l<=h:
+            mid =(l+h)//2
+            if (mid==h or nums[mid]>nums[mid+1]) and (mid==l or nums[mid]>nums[mid-1]):
+                return mid
+            elif nums[mid]<nums[mid+1]:
+                l = mid+1
+            else:
+                h = mid -1
+        return -1
+
+

position_in_sorted_array.py

@@ -0,0 +1,38 @@
+# Find first and last position of element in a sorted array
+# #Using two Binary Search to find the first and last position of an element in a sorted array
+class Solution:
+    def searchRange(self, nums: List[int], target: int) -> List[int]:
+        def binarySearchFirst(nums,l,h,target):
+            while l<=h:
+                mid = (l+h)//2
+                if nums[mid] == target:
+                    if mid == l or nums[mid]!= nums[mid-1]:
+                        return mid
+                    else:
+                        h = mid-1
+                elif nums[mid]>target:
+                    h = mid-1
+                else:
+                    l = mid+1
+            return -1
+
+        def binarySearchLast(nums,l,h,target):
+            while l<=h:
+                mid = (l+h)//2
+                if nums[mid] == target:
+                    if mid == h or nums[mid]!= nums[mid+1]:
+                        return mid
+                    else:
+                        l = mid+1
+                elif nums[mid]>target:
+                    h = mid-1
+                else:
+                    l = mid+1
+
+        first = binarySearchFirst(nums, 0, len(nums)-1, target)
+        if first == -1:
+            return [-1,-1]
+        last = binarySearchLast(nums, first, len(nums)-1, target)
+        return [first,last]
+
+