Finished BinarySearch-2

P1.py

@@ -0,0 +1,19 @@
+# Find peak element in an array
+class Solution:
+    def findPeakElement(self, nums: List[int]) -> int:
+        low = 0
+        high = len(nums)-1
+
+        while low<=high:
+            mid = (low+high)//2
+
+            if (mid==len(nums)-1 or nums[mid] > nums[mid+1]) and (mid ==0 or nums[mid]>nums[mid-1]):
+                return mid
+            elif (mid+1 < len(nums) and nums[mid+1]>= nums[mid]):
+                low = mid+1
+            else:
+                high = mid-1
+        return -1
+
+# TC: O(logN)
+# SC: O(1)

P2.py

@@ -0,0 +1,24 @@
+# Find minimum in rotated sorted array
+class Solution:
+    def findMin(self, nums: List[int]) -> int:
+        low = 0 
+        high = len(nums)-1
+
+
+        while low<=high:
+            if nums[low] <= nums[high]:
+                return nums[low]
+
+            mid = (low+high)//2
+
+            # check for left sorted or right sorted
+            if mid>0 and nums[mid] < nums[mid-1]:
+                return nums[mid]
+
+            if nums[mid] >=  nums[low]: #left sorted
+                low = mid+1
+            elif nums[mid] < nums[high]: #right sorted
+                high = mid-1
+
+        return -1
+

P3.py

@@ -0,0 +1,59 @@
+# Find First and Last Position of Element in Sorted Array
+
+class Solution:
+    def searchRange(self, nums: List[int], target: int) -> List[int]:
+
+        if nums == None or len(nums)==0:
+            return [-1,-1]
+
+        low = 0
+        high = len(nums)-1
+        firstElement = -1
+        secondElement = -1
+
+        firstElement = self.findFirstElement(nums, low, high, target)
+
+        if firstElement == -1:
+            return [-1,-1]
+
+        secondElement = self.findLastElement(nums, firstElement, high, target)
+
+        if secondElement == -1:
+            return [-1,-1]
+
+        return [firstElement, secondElement]
+
+
+    def findFirstElement(self, nums, low, high, target):
+        while low <= high:
+            mid = (low+high)//2
+
+            if nums[mid] == target:
+                if mid==0 or nums[mid]>nums[mid-1]:
+                    return mid
+                else:
+                    high = mid-1
+            elif nums[mid]>target:
+                high = mid-1
+            else:
+                low = mid+1
+        return -1
+
+
+    def findLastElement(self, nums, low, high, target):
+        while low <= high:
+            mid = (low+high)//2
+
+            if nums[mid] == target:
+                if mid==len(nums)-1 or nums[mid]<nums[mid+1]:
+                    return mid
+                else:
+                    low = mid+1
+            elif nums[mid]>target:
+                high = mid-1
+            else:
+                low = mid+1
+        return -1
+
+# TC: O(logN)
+# SC: O(1)