Compare the sum of each element in two lists with the specified value in Python

Introduction

Have you ever wanted to compare the sum of each element with the value you specified when you had two lists? 　 For example

[-1, 3, 8, 2, 9, 5] 　　[4, 1, 2, 10, 5, 20]

Suppose you have two lists.

At that time, it is examined whether a specific value can be expressed by the sum of two elements selected from each list.

If a particular value is 25 and you select (-1, 4), the total is 3, which is different. In that case, only (5, 20) is correct. 　 A YouTube video (see URL below) showed how to solve this problem. This time I wrote the method in Python.

program

I programmed three solutions from the methods introduced. The values to compare are ~~ 24, 25, 26 ~~ 23, 24, 25 (corrected December 13, 2019).

The first is how to add all the elements together.

Brute-force.py

#list
A = [-1, 3, 8, 2, 9, 5]
B = [4, 1, 2, 10, 5, 20]

#Value you want to compare
target = 24

#Brute force
for i in A:
    for j in B:
        if target - 1 <= (i + j) <= target + 1:
            print(str(i) + "When" + str(j) + "Is a pair.")

The next method is to search the contents of the list and then compare.

linear.py

#list
A = [-1, 3, 8, 2, 9, 5]
B = [4, 1, 2, 10, 5, 20]

#Value you want to compare
target = 24

#Linear selection
for i, v in enumerate(B):
    if target - 1 - v in A:
        index = A.index(target - 1 -v)
        print(str(A[index]) + "When" + str(v) + "Is a pair.")
    if target - v in A:
        index = A.index(target - v)
        print(str(A[index]) + "When" + str(v) + "Is a pair.")
    if target + 1 - v in A:
        index = A.index(target + 1 - v)
        print(str(A[index]) + "When" + str(v) + "Is a pair.")

Finally, how to create a matrix. The values to compare are 12, 13, 14.

Matrix.py

#Matrix creation
import numpy as np

#element
A = np.array([7, 4, 1, 10])
B = np.array([4, 5, 8, 7])

#Sort elements in ascending order
A.sort()
B.sort()

target = 13

#Table the addition of all elements
array = np.array([i+j for i in A for j in B]).reshape((len(A), len(B)))

#Target range
column_start = 0            #0
column_end = array.shape[1] #4

#search
for j in reversed(range(array.shape[0])):
    #Upper range
    for i in range(column_start, column_end):  
        if array[i][j] >= target - 1:
            column_start = i
            break
    print(str(A[i]) + "When" + str(B[j]) + "Is a pair.")

What i learned

I learned how to solve a problem with less computational complexity.

in conclusion

To be honest, I didn't know how to use the last method due to lack of study, I would like to continue learning programming. 　 Thank you for visiting.

Reference URL

5 Problem Solving Tips for Cracking Coding Interview Questions (Link to YouTube video)