是否可以在不同于当前数组的数组中找到前一个数字？

def find_previous_in_array(arr1, arr2, target):
    for i in range(len(arr1)):
        if arr1[i] == target:
            # 在arr2中顺序查找前一个数字
            for j in range(len(arr2)):
                if arr2[j] == arr1[i] - 1:
                    return arr2[j]
    return None

# 示例
arr1 = [5, 10, 15]
arr2 = [3, 7, 10, 14, 18]
target = 10
print(find_previous_in_array(arr1, arr2, target))  # 输出: 7

def binary_search_previous(arr, target):
    low, high = 0, len(arr) - 1
    while low <= high:
        mid = (low + high) // 2
        if arr[mid] == target - 1:
            return arr[mid]
        elif arr[mid] < target - 1:
            low = mid + 1
        else:
            high = mid - 1
    return None

def find_previous_in_array_sorted(arr1, arr2, target):
    for num in arr1:
        if num == target:
            return binary_search_previous(arr2, target)
    return None

# 示例
arr1 = [5, 10, 15]
arr2 = [3, 7, 10, 14, 18]
target = 10
print(find_previous_in_array_sorted(arr1, arr2, target))  # 输出: 7