Check if the array is beautiful in Python

Suppose we have an array nums of unique elements. We have to check whether these conditions satisfy or not:

1. Elements will be in range 1 to n.
2. The array must not be sorted in ascending order.

So, if the input is like nums = [2,6,1,5,3,4], then the output will be True.

To solve this, we will follow these steps −

• n := size of nums
• total := nums[0]
• is_sorted := True
• for i in range 1 to n - 1, do
  • if nums[i] is same as nums[i - 1], then
    • return False
  • if nums[i] < nums[i - 1], then
    • is_sorted := False
  • total := total + nums[i]
• if is_sorted is true, then
  • return False
• return true when total is same as sum of first n numbers, otherwise false

Let us see the following implementation to get better understanding −

Example Code

def solve(nums):
   n = len(nums)
   
   total = nums[0]
   is_sorted = True
   
   for i in range(1,n):
      if nums[i] == nums[i - 1]:
         return False
  
      if nums[i] < nums[i - 1]:
         is_sorted = False
      total += nums[i]
   
   if is_sorted:
      return False
  
   return total == (n * (n + 1) // 2)
 
nums = [2,6,1,5,3,4]
print(solve(nums))

Input

[2,6,1,5,3,4]

Output

True