# Python – Rearrange elements second index greater than first

Given 2 lists, for a given index, 2nd list element is always larger than first, and if not, we rearrange it.

Input : test_list1 = [36, 38, 40, 132], test_list2 = [35, 37, 39, 41, 133]
Output : [37, 39, 41, 133]
Explanation : Each element in result list is greater than its index counterpart of 1st list. (Eg. 37 > 36)

Input : test_list1 = [2, 6], test_list2 = [5, 3, 8]
Output : [5, 8]
Explanation : Here 5 > 2 and 8 > 6.

Method 1: Using loop This is brute way to tackle this problem. In this, we try to get best suitable next higher element after the whole list traversal and perform the necessary rearrangement.

## Python3

 `# Python3 code to demonstrate working of ``# Rearrange elements second index greater than first``# Using loop` `# initializing lists``test_list1 ``=` `[``14``, ``16``, ``18``, ``110``]``test_list2 ``=` `[``13``, ``15``, ``17``, ``19``, ``111``]`  `# printing original lists``print``("The original ``list` `1` `is` `: " ``+` `str``(test_list1))``print``("The original ``list` `2` `is` `: " ``+` `str``(test_list2))` `# Rearrange elements second index greater than first``# Using loop``x ``=` `y ``=` `0``res1, res2 ``=` `[], []``while` `x < ``len``(test_list2) ``and` `y < ``len``(test_list1):``    ` `    ``# checking for greater element``    ``if` `test_list2[x] > test_list1[y]:``        ``res2.append(test_list2[x])``        ``res1.append(test_list1[y])``        ``while` `y < ``len``(test_list1) ``and` `test_list2[x] > test_list1[y]:``            ``res1[``-``1``] ``=` `test_list1[y]``            ``y ``+``=` `1``    ``x ``+``=` `1` `# printing result ``print``("``List` `2` `after conversion : " ``+` `str``(res2))`

Output :
```The original list 1 is : [14, 16, 18, 110]
The original list 2 is : [13, 15, 17, 19, 111]
List 2 after conversion : [15, 17, 19, 111]```

Time complexity: O(n), where n is the length of test_list1 + test_list2.
Auxiliary Space: O(n), where n is the length of test_list1 + test_list2. The additional space is used to store the rearranged lists res1 and res2.

Method 2: Using list comprehension

## Python3

 `# Python3 code to demonstrate working of``# Rearrange elements second index greater than first``# Using list comprehensions` `# initializing lists``test_list1 ``=` `[``14``, ``16``, ``18``, ``110``]``test_list2 ``=` `[``13``, ``15``, ``17``, ``19``, ``111``]`  `# printing original lists``print``(``"The original list 1 is : "` `+` `str``(test_list1))``print``(``"The original list 2 is : "` `+` `str``(test_list2))` `# Rearranging elements in list 2 such that the second index is greater than the first``x ``=` `0``res2 ``=` `[test_list2[i] ``for` `i ``in` `range``(``len``(test_list2)) ``if` `x < ``len``(test_list1) ``and` `test_list2[i] > test_list1[x]]``x ``=` `[i ``for` `i ``in` `range``(``len``(test_list1)) ``if` `x < ``len``(test_list2) ``and` `test_list2[x] > test_list1[i]]` `# printing result``print``(``"List 2 after conversion : "` `+` `str``(res2))``#This code is contributed by Vinay pinjala.`

Output
```The original list 1 is : [14, 16, 18, 110]
The original list 2 is : [13, 15, 17, 19, 111]
List 2 after conversion : [15, 17, 19, 111]```

Time complexity: O(n)
Auxiliary Space: O(n)

Previous
Next