Repeating outputs in Python

Question

This code keep repeating the same sets of numbers that add up to a specific number. ex: 31+ 69 = 100. This will be repeated many times among other possibilities. What's the matter with my code ? enter image description here

Thanks. Here it is:

import random

target_number = int(input('Input a number and we will return a list of two numbers that equate to this number'))

r1 = range(1,target_number)
r2 = range(1,target_number)

while True:
    for i in range(24):
        num1 = random.choice(r1)
        num2 = random.choice(r2)
        if num1 + num2 == target_number:
            print(f"solved: {num1}+{num2} = {target_number}")

What's the for i in range(24) for? Do you want to print 24 pairs of numbers? — Ignatius Reilly
– Ignatius Reilly, Commented Aug 28, 2022 at 1:45
The outer while True loop has no way to exit. So it will run forever. What were you expecting to happen? — John Gordon
– John Gordon, Commented Aug 28, 2022 at 1:46
Using random numbers is highly inefficient. You might quickly get unique pairs in the beginning, but it will get increasingly harder to get all pairs. You want to generate combinations — mozway
– mozway, Commented Aug 28, 2022 at 1:46
You could set num1 to be random and just make num2 = target - num1... — Ignatius Reilly
– Ignatius Reilly, Commented Aug 28, 2022 at 1:49

dsagman · Accepted Answer · 2022-08-28 01:40:09Z

1

As noted by HuLu, while True will run forever. The for loop with i could be removed as follows:

import random

target_number = int(input('Input a number and we will return a list of two numbers that equate to this number'))

r1 = range(1,target_number)
r2 = range(1,target_number)

while True:
    num1 = random.choice(r1)
    num2 = random.choice(r2)
    if num1 + num2 == target_number:
        print(f"solved: {num1}+{num2} = {target_number}")
        break

answered Aug 28, 2022 at 1:40

dsagman

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Comments

Dina Kisselev · Accepted Answer · 2022-08-28 02:13:11Z

1

If you're looking to find all pairs that add up to your number, try the following:

def find_factors(x):
    for i in range(x): # loop through all numbers (until x)
        if i <= x-i: # this is to avoid printing duplicate pairs, e.g. (2,3) and (3,2)
            print([i,x-i]) # print i, and i subtracted from x

This function will take x as an argument and return all pairs of integers that add up to x.

E.g. calling find_factors(5) will return:

[0, 5]
[1, 4]
[2, 3]

edited Aug 28, 2022 at 2:13

answered Aug 28, 2022 at 1:44

Dina Kisselev

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13 Comments

Dina Kisselev Over a year ago

^^ Now that I read your question again, it looks like you were interested in finding a single (random) pair only. As @mozway pointed out -- you may need all combinations, so my code will help you get them.

mozway Over a year ago

Much better approach than the original one (+1), still one could do even better by directly generating the pairs of numbers that add up to 100. (100+0, 99+1, 98+2...) without any test ;)

Mr. Green Over a year ago

Without the "while true" it only gives me 1 output. I want a list of outputs but I don't want to print dublicate pairs.

mozway Over a year ago

@Mr.Green pairs = [(i, 100-i) for i in range(51)] that's it.

Dina Kisselev Over a year ago

@mozway -- we may want to replace 100 with a generic x: [(i, x-i) for i in range(int(x/2+1))]

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HuLu ViCa · Accepted Answer · 2022-08-28 01:41:58Z

0

while True means "repeat forever", you have to put and end to the loop:

import random

target_number = int(input('Input a number and we will return a list of two numbers that equate to this number'))

r1 = range(1,target_number)
r2 = range(1,target_number)

cont = True
while cont:
    for i in range(24):
        num1 = random.choice(r1)
        num2 = random.choice(r2)
        if num1 + num2 == target_number:
            print(f"solved: {num1}+{num2} = {target_number}")
            cont = False

edited Aug 28, 2022 at 1:41

answered Aug 28, 2022 at 1:35

HuLu ViCa

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1 Comment

Mr. Green Over a year ago

I have a list of possible numbers adding to eg: 100, but most repeat themselves at least 15 times, the same 31+69 = 100. How to only have 1 (31+69 =100) ? thanks

Vivek Maddeshiya · Accepted Answer · 2022-08-28 02:00:13Z

0

use break as soon as you find numbers with a sum of target_number in if statement.Otherwise this while loop will run forever.

answered Aug 28, 2022 at 2:00

Vivek Maddeshiya

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