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Python Challenges: Find three numbers from an array such that the sum of three numbers equal to zero

Python Challenges - 1: Exercise-9 with Solution

Write a Python program to find three numbers from an array such that the sum of three numbers equal to zero.

Explanation:

Python: Sum of three numbers equal to zero

Sample Solution:-

Python Code:

# return a list of lists of length 3 
def three_Sum(num):
    if len(num)<3: return []
    num.sort()
    result=[]
    for i in range(len(num)-2):
        left=i+1
        right=len(num)-1
        if i!=0 and num[i]==num[i-1]:continue
        while left<right:
            if num[left]+num[right]==-num[i]:
                result.append([num[i],num[left],num[right]])
                left=left+1
                right=right-1
                while num[left]==num[left-1] and left<right:left=left+1
                while num[right]==num[right+1] and left<right: right=right-1
            elif num[left]+num[right]<-num[i]:
                left=left+1
            else:
                right=right-1
    return result
 
nums1=[-1,0,1,2,-1,-4]
nums2 = [-25,-10,-7,-3,2,4,8,10]
print(three_Sum(nums1))
print(three_Sum(nums2))

Sample Output:

[[-1, -1, 2], [-1, 0, 1]]                                                                                     
[[-10, 2, 8], [-7, -3, 10]] 

Flowchart:

Python Flowchart: Find three numbers from an array such that the sum of three numbers equal to zero

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Python: Tips of the Day

Python: Kwargs

**kwargs and *args are function arguments that can be very useful.

They are quite underused and often under-understood as well.

Let's try to explain what kwargs are and how to use them.

  • While *args are used to pass arguments at an unknown amount to functions, **kwargs are used to do the same but with named arguments.
  • So, if *args is a list being passed as an argument, you can think of **kwargs as a dictionary that's being passed as an argument to a function.
  • You can use arguments as you wish as long as you follow the correct order which is: arg1, arg2, *args, **kwargs. It's okay to use only one of those but you can't mix the order, for instance, you can't have: function(**kwargs, arg1), that'd be a major faux pas in Python.
  • Another example: You can do function(*args,**kwargs) since it follows the correct order.
  • Here is an example. Let's say satelites are given with their names and weight in tons in dictionary format. Code prints their weight as kilograms along with their names.
def payloads(**kwargs):
    for key, value in kwargs.items():
        print( key+" |||", float(value)*100)
payloads(NavSat1 = '2.5', BaysatG2 = '4')

Output:

NavSat1 ||| 250.0
BaysatG2 ||| 400.0

Since the function above would work for any number of dictionary keys, **kwargs makes perfect sense rather than passing arguments with a fixed amount.

def payloads(**kwargs):
    for key, value in kwargs.items():
        print( key+" |||", float(value)*100)

sats={"Tx211":"3", "V1":"0.50"}
payloads(**sats)

Output:

Tx211 ||| 300.0
V1 ||| 50.0