How do you find all pairs of an integer array whose sum is equal to a given number?

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#1

Hey guys,

In my opinion this is hard to solve, anyways for you not?

What I want to do?

How do you find all pairs of an integer array whose sum is equal to a given number.

For example, if the input integer array is {2, 7, 3, 9, 11} and given sum is 10, the output should be {7,3}.

So you may think this looks easy to solve but dont think about it, if you think long then you know that this problem sounds not easy - when you never code something like that.
This is what I have been created so far but it doesnt seem work well, maybe you find the problem or the mistake I did here.

local numbers = {3,6,4,2,1,5,2}

function sumwewant(array, sum)
	for i = 1, #array do
		local first = array[i]
		for j = 1, #array do
			local second = numbers[j]
			if ((first + second) == sum)then
				print(first, second)
			end
		end
	end
end

local d  = sumwewant(numbers, 10)
print(d)
1 Like
#2

This is an interesting and hard question to answer. This is the best I can do.

local function(array,sumWeWant)
    for i = 1, #array, do
        local first = array[1]
        for j = (i + 1), #array do
            local second = array(j)
            local result = first + second
            if result == sumWeWant then
                return result
            else return end
         end
    end
end

I think this is what you’re looking for.

1 Like
#3

Output is:

ServerScriptService.Script:7: attempt to call a table value

local numbers = {3,6,4,2,1,5,2}

local function findarray(array,sumWeWant)
	for i = 1, #array do
		local first = array[1]
		for j = (i + 1), #array do
			local second = array(j)
			local result = first + second
			local d = sumWeWant
			if result == result then
				return result
			else return end
		end
	end
end


local d = findarray(numbers, 10)
print(d)
1 Like
#4

Whoops, not suppose to be brackets AKA (), should be square ones AKA [].

1 Like
#5

Whoops, not suppose to be brackets AKA (), should be square ones AKA [].

I cant follow you AKA? () → [] I am a bit lost

1 Like
#6

Just change

array(j)

To

array[j]
1 Like
#7

I don’t see the issue, your code works fine

1 Like
#8

oh yes it must be [], but anyways.
still got nill

local numbers = {3,6,4,2,1,5,2}

local function findarray(array,sumWeWant)
	for i = 1, #array do
		local first = array[1]
		for j = (i + 1), #array do
			local second = array[j]
			local result = first + second
			local de = sumWeWant
			if result == de then
				return result
			else return end
		end
	end
end


local d = findarray(numbers, 10)
print(d)
1 Like
#9

Are you trying to make “findarray” return an array of all the number pairs?

#10

which one you mean my or ItzMezeus?

#11

Your code works fine. If the issue is that it’s printing nil then change the function to return an array with all the matched number because your function isn’t returning anything

local numbers = {3,6,4,2,1,5,2}

function sumwewant(array, sum)
	local matches = {}
	for i = 1, #array do
		local first = array[i]
		for j = 1, #array do
			local second = numbers[j]
			if ((first + second) == sum)then
				table.insert(matches, {first, second})
			end
		end
	end
	return matches
end

local d  = sumwewant(numbers, 10)
print(d)

image

#12

but where comes the 5, 5 in the table is nowhere a 5, 5
I mean if you look at my array

#13

That’s because it’s checking the same number twice, in the 2nd loop you should add a check so i ~= j

local numbers = {3,6,4,2,1,5,2}

function sumwewant(array, sum)
	local matches = {}
	for i = 1, #array do
		local first = array[i]
		for j = 1, #array do
			if i ~= j then
				local second = numbers[j]
				if ((first + second) == sum)then
					table.insert(matches, {first, second})
				end
			end
		end
	end
	return matches
end

local d  = sumwewant(numbers, 10)
print(d)

image

#14

I knew it loop different but actually I cant figure out how to make it work well for loop

#15

this isnt good what if I want add in my table a 5 now?

#16

yea I think you know what would happen

#17

image

#18

You could check if the pair already exists and skip over it

#19

your script doesnt work why dont you answer anymore?

#20

this woudnt make it better and it would trash at more than 4 fives in the script