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Binary Search

HW

def search_rotated_array(arr, target):
    left = 0
    right = len(arr) - 1

    while left <= right:
        mid = (left + right) // 2

        if arr[mid] == target:
            return target  

        if arr[left] <= arr[mid]:
            if arr[left] <= target < arr[mid]:
                right = mid - 1
            else:
                left = mid + 1
        else:
            if arr[mid] < target <= arr[right]:
                left = mid + 1
            else:
                right = mid - 1

    return -1  


arr = [4, 5, 6, 7, 0, 1, 2]
target = 1
print(search_rotated_array(arr, target))
1
def find_first_last_occurrence(arr, target):
    def find_first():
        left, right = 0, len(arr) - 1
        index = -1
        while left <= right:
            mid = (left + right) // 2
            if arr[mid] == target:
                index = mid
                right = mid - 1  
            elif arr[mid] < target:
                left = mid + 1
            else:
                right = mid - 1
        return index

    def find_last():
        left, right = 0, len(arr) - 1
        index = -1
        while left <= right:
            mid = (left + right) // 2
            if arr[mid] == target:
                index = mid
                left = mid + 1  
            elif arr[mid] < target:
                left = mid + 1
            else:
                right = mid - 1
        return index

    first = find_first()
    last = find_last()

    if first == -1 or last == -1:
        return -1
    return (first, last)

arr = [1, 2, 2, 2, 3, 4, 5]
target = 2
print(find_first_last_occurrence(arr, target))
(1, 3)
def find_smallest_greater_or_equal(arr, target):
    left, right = 0, len(arr) - 1
    result = -1

    while left <= right:
        mid = (left + right) // 2

        if arr[mid] >= target:
            result = arr[mid]  
            right = mid - 1
        else:
            left = mid + 1

    return result

arr = [1, 3, 5, 7, 9, 11]
target = 8
print(find_smallest_greater_or_equal(arr, target))  
9