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leetcode 1198 Premium question (https://github.com/doocs/leetcode/blob/main/solution/1100-1199/1198.Find%20Smallest%20Common%20Element%20in%20All%20Rows/README_EN.md)

G4 Interview Template

Today's Interview Question
You are given a string s, which contains stars *.

In one operation, you can:

Choose a star in s.
Remove the closest non-star character to its left, as well as remove the star itself.
Return the string after all stars have been removed.

Note:

The input will be generated such that the operation is always possible.
It can be shown that the resulting string will always be unique.


Example 1:
Input: s = "leet**cod*e"
Output: "lecoe"
Explanation: Performing the removals from left to right:
- The closest character to the 1st star is 't' in "leet**cod*e". s becomes "lee*cod*e".
- The closest character to the 2nd star is 'e' in "lee*cod*e". s becomes "lecod*e".
- The closest character to the 3rd star is 'd' in "lecod*e". s becomes "lecoe".
There are no more stars, so we return "lecoe".

Example 2:
Input: s = "erase*****"
Output: ""
Explanation: The entire string is removed, so we return an empty string.

Constraints:

1 <= s.length <= 10**5
s consists of lowercase English letters and stars *.
The operation above can be performed on s.

def fun(s):
    stack = []
    for c in s:
        if c != "*":
            stack.append(c)
        else:
            stack.pop()
    return "".join(stack) 
print(fun("erase*****"))

A phrase is a palindrome if, after converting all uppercase letters into lowercase letters and removing all non-alphanumeric characters, it reads the same forward and backward. Alphanumeric characters include letters and numbers.

Given a string s, return true if it is a palindrome, or false otherwise.

 

Example 1:

Input: s = "A man, a plan, a canal: Panama"
Output: true
Explanation: "amanaplanacanalpanama" is a palindrome.
Example 2:

Input: s = "race a car"
Output: false
Explanation: "raceacar" is not a palindrome.
Example 3:

Input: s = " "
Output: true
Explanation: s is an empty string "" after removing non-alphanumeric characters.
Since an empty string reads the same forward and backward, it is a palindrome.
 

Constraints:

1 <= s.length <= 2 * 105
s consists only of printable ASCII characters.

"""

Question Denoscription
    Given an input string s, reverse the order of the words.

    A word is defined as a sequence of non-space characters. The words in s will be separated by at least one space.

    Return a string of the words in reverse order concatenated by a single space.

    Note that s may contain leading or trailing spaces or multiple spaces between two words. 
    The returned string should only have a single space separating the words. Do not include any extra spaces.



    Example 1:

    Input: s = "the sky is blue"
    Output: "blue is sky the"
    Example 2:

    Input: s = "  hello world  "
    Output: "world hello"
    Explanation: Your reversed string should not contain leading or trailing spaces.
    Example 3:

    Input: s = "a good   example"
    Output: "example good a"
    Explanation: You need to reduce multiple spaces between two words to a single space in the reversed string.
 

Constraints:

    1 <= s.length <= 104
    s contains English letters (upper-case and lower-case), digits, and spaces ' '.
    There is at least one word in s.
    
    
    "a good   example"
["a","good","example"]
      L  R
 
 
 [example,"good","a"]


"""

#will s will split
#variables left->0 rght ->len(splited)-1
#will have  a while l<L    left+=1 righ-=1 


def revercing_word(s):
    words=[] 
    for word in s.split(" "):
        if word:
            words.append(word)
    
    left=0
    right=len(words)-1
    
    
    while left<right:
        words[left],words[right]= words[right],words[left]
        left+=1
        right-=1
        
    return " ".join(words)
print(revercing_word("hello world"))

You are given a 0-indexed integer array nums.
Swaps of adjacent elements are able to be performed on nums.
A valid array meets the following conditions:
    The largest element (any of the largest elements if there are multiple) is at the rightmost position in the array.
    The smallest element (any of the smallest elements if there are multiple) is at the leftmost position in the array.
Return the minimum swaps required to make nums a valid array.
 
Example 1:
Input: nums = [3,4,5,5,3,1]
Output: 6
Explanation: Perform the following swaps:
- Swap 1: Swap the 3rd and 4th elements, nums is then [3,4,5,3,5,1].
- Swap 2: Swap the 4th and 5th elements, nums is then [3,4,5,3,1,5].
- Swap 3: Swap the 3rd and 4th elements, nums is then [3,4,5,1,3,5].
- Swap 4: Swap the 2nd and 3rd elements, nums is then [3,4,1,5,3,5].
- Swap 5: Swap the 1st and 2nd elements, nums is then [3,1,4,5,3,5].
- Swap 6: Swap the 0th and 1st elements, nums is then [1,3,4,5,3,5].
It can be shown that 6 swaps is the minimum swaps required to make a valid array.

Example 2:
Input: nums = [9]
Output: 0
Explanation: The array is already valid, so we return 0.

    
          
 
Constraints:
1 <= nums.length <= 10^5
1 <= nums[i] <= 10^5

You are given a sorted array nums of size n and an integer target. 
Your task is to find the pair of numbers in the array whose sum is less than or equal to the target and has the largest possible sum.

Return the maximum sum of such a pair. If no valid pair exists, return -1.

Example 1:
Input: nums = [2, 3, 5, 8, 13], target = 10
Output: 10
 l
[2, 3, 5, 8, 13],
          r
[7,8 , 10]
Explanation: The pair (2, 8) has a sum of 10, which is the largest possible sum less than or equal to 10.

Example 2:
Input: nums = [1, 1, 1, 1], target = 1
Output: -1
Explanation: No pair has a sum less than or equal to 1.

Constraints:
1<=n<=10⁵
Nums  is sorted in non-decreasing order.



def targetSum(nums , target):
    left = 0
    max_ = -1
    right = len(nums)-1
    while left < right:
        sum = nums[left] + nums[right]
        if sum == target:
            return sum
        elif sum > target:
            right -=1
        elif sum < target:
            left += 1
            max_ = max(max_,sum)
    return max_