CA 13 - Move Zeros

 Move Zeroes

Given an integer array nums, move all 0's to the end of it while maintaining the relative order of the non-zero elements.
Note that you must do this in-place without making a copy of the array.

Example 1:

    Input: nums = [0,1,0,3,12]

    Output: [1,3,12,0,0]

Example 2:

    Input: nums = [0]

    Output: [0]

CODE:

    Intuitive way of solving this problem is by assigning two array shuch that both contains non-zero values and zero values separately and then finally add them such that all the zeros fall at the end of the array. 


class Solution:
    def moveZeroes(self, nums: List[int]) -> None:
        n = len(nums)
        nonzero = []
        zero =[]
        for i in nums:
            if i == 0:
                zero.append(0)
            else:
                nonzero.append(i)
        newnum = nonzero+zero
        for i in range(0,n):
            nums[i] = newnum[i]

       

     Here the new arrays take the extra spacing, thus to avoid this we will make no new array and do in place swapping with the help of two pointers and condition based on our question. We will place two pointers left and right, if we encounter a "0" we will move the right pointer, if we encounter a non-zero value we will replace it with the left pointer value (which points to zero) and then move both the left and right pointer.


class Solution:
    def moveZeroes(self, nums: List[int]) -> None:
        l = 0
        r = 0
        while r < len(nums):
            if nums[r]:
                nums[l],nums[r] = nums[r],nums[l]
                l+=1
            r+=1


Comments

Post a Comment

Popular posts from this blog

CA 04 - Two Sum & Sorted Two Sum

Image
  MY CODE: In brute force method the intuitive way of solving this problem with two for loop. Using nested loop to traverse through the list and try different combination of two sum to check if it matches with the target.    Time complexity: O(n^2)       OPTIMIZED:          In the optimized method of approaching the Two Sum problem. The given list is already sorted in ascending order. This gives us the leverage of using Two pointer technique to solve this problem. Thus using single loop to approach this problem. If current sum is less than target move the left pointer, if it is greater move the right pointer else return the current index (equal to target).  Time complexity: O(n) MY CODE:
Read more

CA 05 - Reverse the array

  Array Reverse Reverse an array  arr[] . Reversing an array means  rearranging  the elements such that the  first  element becomes the  last , the  second  element becomes  second last  and so on. Input: arr[] = [1, 4, 3, 2, 6, 5] Output: [5, 6, 2, 3, 4, 1] Explanation: The first element 1 moves to last position, the second element 4 moves to second-last and so on. Input: arr[] = [4, 5, 1, 2] Output: [2, 1, 5, 4] Explanation: The first element 4 moves to last position, the second element 5 moves to second last and so on. CODE:     BRUTE FORCE METHOD:          Here, in this method we will create a temporary array to store the reversed given array and then assign it to the given array class Solution :     def reverseArray ( arr ):         n = len (arr)         temp = [ 0 ] * n         for i in range (n- 1 ,- 1 ,- 1 ): ...
Read more

CA 21 - Basic Select SQL Queries

Image
 1.  Query all columns for a city in   CITY   with the   ID   1661 . The  CITY  table is described as follows: Here we make use of the where conditon cllause to retrieve the details of the Id with 1661, we select all the columns to be displayed and "*" is avoided for best practice. SOLUTION: SELECT ID,NAME,COUNTRYCODE,DISTRICT,POPULATION FROM CITY where ID = 1661 ; 2. Query all columns for all American cities in the   CITY   table with populations larger than   100000 . The   CountryCode   for America is   USA . The  CITY  table is described as follows: Here we make use of the where condtional clause, to obatin the population to be over thhe given number we make use of the' >' symbol to achieve this. Also the AND operator is used to state two where conditons where we want only the details of cities in USA so we use the countrycode check with 'USA' single quotes are used to check with the value, usage ...
Read more