Choose the outermost elements from an array and combine them

Question

Choose the outermost elements from an array and combine them

Given an array such as [0,1,2,3,4,5], where the length is always even.

How can I select and pair elements starting from the leftmost and rightmost positions all the way to the center?

For example, in the array above, it should result in [[0,5],[1,4],[2,3]]

I have already attempted a solution which can be seen here

const arr = [0,1,2,3,4,5]

const result = []
const possibleMatches = arr.length / 2

for (let x = 0; x < possibleMatches; x++) {
  result.push([arr[x], arr[arr.length - x - 1]])
}

console.log(result)
//[ [ 0, 5 ], [ 1, 4 ], [ 2, 3 ] ]

However, are there better approaches than using a for loop? Perhaps utilizing one-line arrow functions?

javascript arrays

Answer 1

Answer №1

element, you can divide the array into two halves using Array.splice. Afterward, iterate over the array with the map method and apply the same logic as in your for loop to access elements from the "right" side:

For example:

const arr = [0, 1, 2, 3, 4, 5]

const result = arr.splice(0, arr.length / 2).map((e, i) => [e, arr[arr.length - i - 1]])

console.log(result)

Answer 2

element, you can divide the array into two halves using Array.splice. Afterward, iterate over the array with the map method and apply the same logic as in your for loop to access elements from the "right" side:

For example:

const arr = [0, 1, 2, 3, 4, 5]

const result = arr.splice(0, arr.length / 2).map((e, i) => [e, arr[arr.length - i - 1]])

console.log(result)

Answer 3

Answer №2

One way to create a new array with half the size of the original is by using `Array.from()` and selecting values from both ends of the original array:

const arr = [0,1,2,3,4,5]

const result = Array.from(
  { length: Math.ceil(arr.length / 2) },
  (_, i) => [arr[i], arr[arr.length - 1 - i]]
)

console.log(result)

If your environment supports it, you can also use Array.at() to achieve this without needing to calculate the length:

const arr = [0,1,2,3,4,5]

const result = Array.from(
  { length: Math.ceil(arr.length / 2) },
  (_, i) => [arr.at(i), arr.at(-i-1)]
)

console.log(result)

Answer 4

One way to create a new array with half the size of the original is by using `Array.from()` and selecting values from both ends of the original array:

const arr = [0,1,2,3,4,5]

const result = Array.from(
  { length: Math.ceil(arr.length / 2) },
  (_, i) => [arr[i], arr[arr.length - 1 - i]]
)

console.log(result)

If your environment supports it, you can also use Array.at() to achieve this without needing to calculate the length:

const arr = [0,1,2,3,4,5]

const result = Array.from(
  { length: Math.ceil(arr.length / 2) },
  (_, i) => [arr.at(i), arr.at(-i-1)]
)

console.log(result)

Answer 5

Answer №3

rearrange the array by flipping and merging its halves.

check out this single line of code solution:

const numbers = [0,1,2,3,4,5]

const arrangedArray = numbers.slice(numbers.length / 2 * -1).reverse().map((element, index) => [numbers[index],element])
const halfLength = numbers.length / 2

console.log(arrangedArray)

Answer 6

rearrange the array by flipping and merging its halves.

check out this single line of code solution:

const numbers = [0,1,2,3,4,5]

const arrangedArray = numbers.slice(numbers.length / 2 * -1).reverse().map((element, index) => [numbers[index],element])
const halfLength = numbers.length / 2

console.log(arrangedArray)

Answer 7

Answer №4

Implementing a straightforward for loop that iterates from both ends

const arr = [0, 1, 2, 3, 4, 5];

let results = [],
  start = 0,
  end = arr.length - 1;
  
for (; start < end; start++, end--) {
  results.push([arr[start], arr[end]]);
}

console.log(JSON.stringify(results));

or utilizing a while loop

const arr = [0, 1, 2, 3, 4, 5];

const output = [];

while (arr.length > 1) {
  output.push([arr.shift(), arr.pop()]);
}

console.log(JSON.stringify(output));

Answer 8

Implementing a straightforward for loop that iterates from both ends

const arr = [0, 1, 2, 3, 4, 5];

let results = [],
  start = 0,
  end = arr.length - 1;
  
for (; start < end; start++, end--) {
  results.push([arr[start], arr[end]]);
}

console.log(JSON.stringify(results));

or utilizing a while loop

const arr = [0, 1, 2, 3, 4, 5];

const output = [];

while (arr.length > 1) {
  output.push([arr.shift(), arr.pop()]);
}

console.log(JSON.stringify(output));

Choose the outermost elements from an array and combine them

Answer №1

Answer №2

Answer №3

Answer №4

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