Using JavaScript to retrieve and compare element values for a total sum

Question

Using JavaScript to retrieve and compare element values for a total sum

Given two arrays, the goal is to determine if any two numbers in the array add up to 9.

The function should return either true or false.

For example:

array1 [1, 2, 4, 9] has no pair that sums up to 9, so it returns false

array2 [1, 2, 4, 5] does have a pair (4 and 5) that adds up to 9, so it returns true

To achieve this, you can use the following JavaScript function:


function hasPairWithSum(arr, sum) {
    var len = arr.length;
    for(var i=0; i<len-1; i++) {
        for(var j=i+1; j<len; j++) {
            if (arr[i] + arr[j] === sum)
                return true;
        }
    }

    return false;
}

console.log(hasPairWithSum([1, 2, 4, 9], 9));

console.log(hasPairWithSum([1, 2, 4, 5], 9));

If you're looking for an alternative approach to solving this problem, feel free to experiment further!

javascript arrays

Answer 1

Answer №1

function FindingPair(arr, total) {
  return arr.some((num1, index1) => arr.some((num2, index2) => num1 + num2 === total && index1 !== index2))
}

console.log(FindingPair([1, 2, 4, 9], 9));
console.log(FindingPair([1, 2, 4, 5], 9));

Answer 2

function FindingPair(arr, total) {
  return arr.some((num1, index1) => arr.some((num2, index2) => num1 + num2 === total && index1 !== index2))
}

console.log(FindingPair([1, 2, 4, 9], 9));
console.log(FindingPair([1, 2, 4, 5], 9));

Answer 3

Answer №2

This particular method offers a quick and efficient solution.

function findPair(arr, S) {

  var hashTable = {};

  // Iterate through each element in array
  for (var i = 0; i < arr.length; i++) {

    // Calculate the difference between S and the current element
    var diff = S - arr[i];

    // Check if this number exists in the hash table
    // If it does, then we have found a pair of numbers that add up to S
    if (hashTable[diff.toString()] !== undefined) {
      return true;
    }

    // Add the current number to the hash table
    hashTable[arr[i].toString()] = arr[i];

  }

  // Return false by default
  return false;

}

console.log(findPair([3, 5, 2, -4, 8, 11], 7));

This approach leverages the use of hash tables.

Answer 4

This particular method offers a quick and efficient solution.

function findPair(arr, S) {

  var hashTable = {};

  // Iterate through each element in array
  for (var i = 0; i < arr.length; i++) {

    // Calculate the difference between S and the current element
    var diff = S - arr[i];

    // Check if this number exists in the hash table
    // If it does, then we have found a pair of numbers that add up to S
    if (hashTable[diff.toString()] !== undefined) {
      return true;
    }

    // Add the current number to the hash table
    hashTable[arr[i].toString()] = arr[i];

  }

  // Return false by default
  return false;

}

console.log(findPair([3, 5, 2, -4, 8, 11], 7));

This approach leverages the use of hash tables.

Answer 5

Answer №3

Here is an innovative method utilizing a generator function combined with recursion to create pairs, along with an includes function that utilizes an iterator and predicate for testing items against the generator:

function* generatePairs(arr) {
  if (!arr.length) return false;
  const [head, ...tail] = arr;
  for (let value of tail) {
    console.log(`[${head}, ${value}]`);
    yield [head, value];
  }
  yield* generatePairs(tail);
}

function checkIfIncludes(iterator, predicate) {
  let result = iterator.next();
  while (!result.done) {
    if (predicate(...result.value)) {
      return true;
    }
    result = iterator.next();
  }
  return false;
}

const calculateSumEquals = sum => (num1, num2) => num1 + num2 === sum;
const pairValuesEqual = ([x, y]) => (m, n) => x === m && y === n;

console.log(checkIfIncludes(generatePairs([2, 4, 9]), calculateSumEquals(9)));
console.log(checkIfIncludes(generatePairs([2, 4, 5]), calculateSumEquals(6)));
console.log(checkIfIncludes(generatePairs([2, 4, 5]), pairValuesEqual([2, 5])));

Answer 6

Here is an innovative method utilizing a generator function combined with recursion to create pairs, along with an includes function that utilizes an iterator and predicate for testing items against the generator:

function* generatePairs(arr) {
  if (!arr.length) return false;
  const [head, ...tail] = arr;
  for (let value of tail) {
    console.log(`[${head}, ${value}]`);
    yield [head, value];
  }
  yield* generatePairs(tail);
}

function checkIfIncludes(iterator, predicate) {
  let result = iterator.next();
  while (!result.done) {
    if (predicate(...result.value)) {
      return true;
    }
    result = iterator.next();
  }
  return false;
}

const calculateSumEquals = sum => (num1, num2) => num1 + num2 === sum;
const pairValuesEqual = ([x, y]) => (m, n) => x === m && y === n;

console.log(checkIfIncludes(generatePairs([2, 4, 9]), calculateSumEquals(9)));
console.log(checkIfIncludes(generatePairs([2, 4, 5]), calculateSumEquals(6)));
console.log(checkIfIncludes(generatePairs([2, 4, 5]), pairValuesEqual([2, 5])));

Using JavaScript to retrieve and compare element values for a total sum

Answer №1

Answer №2

Answer №3

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