CODEWITHSUNDEEP
javascriptarrays
Yoël Zerbib
Yoël Zerbib

Reputation: 187

Need help on thinking about how to solve my problem

I want to replace my for loop by higher order functions in my problem.

I need to create a function that takes an array as parameter and return an array with the values of the input array that match x, let's say 10.

For exemple

const matchesValues = ( array ) => {
    //MyFunc
} 
console.log(matchesValues([2,8,5,5,6])) // [[2,8], [5,5]]

Here is what I have done for the moment:

const matchesValues = (array) => {
  if (array.length > 1) {
    const matches = []
    for (let i = array.length - 1; i >= 0; i--) {
      if (i - 1 >= 0) {
        if (array[i] + array[i - 1] == 10) {
          matches.push([array[i - 1], array[i]])
        }
      }
    }
    return matches
  }
}

console.log(matchesValues([2,8,5,5,5,6])) // expected : [2,8,5,5], recieved : [[5,5], [5,5], [2,8]]

Note that the order would stay the same, but this I can handle.

By which higher order function(s) would you replace my forloop ?

Thanks a lot for your time.

Upvotes: 0

Views: 46

Answers (2)

sonkatamas
sonkatamas

Reputation: 621

there is a longer solution here but with the same return result format [[2,8], [5,5]] what you requested. Also it handles the case when there is only 1 value that matches up the sum, e.g.: 10.

const matchValues = (array, valueToMatch) => {
  const matchingValues = [];
  if(!array.length) {
      return matchingValues;
  }
  array.forEach((actualValue, index) => {
     if((array.length-1) === index) {
         if(actualValue === valueToMatch) {
            matchingValues.push([actualValue]);
         }
     }
     const clonedArray = array.filter((_, clonedValueIndex) => clonedValueIndex !== index);
     clonedArray.forEach((value) => {
       if((value + actualValue) === valueToMatch) {
         let alreadyMatched = false;
         if(matchingValues.length) {
           matchingValues.forEach((matchingValue) => {
             if(matchingValue.includes(value) && matchingValue.includes(actualValue) && (value + actualValue === valueToMatch)) {
              alreadyMatched = true;
             }
           })
         }
         if(!alreadyMatched) {
          matchingValues.push([actualValue, value]);
         }
       }
     })
  });
  return matchingValues;
}

const returnedMatchingvalues = matchValues([2,8,5,5,5,6,10], 10);
console.log(returnedMatchingvalues); // [ [ 2, 8 ], [ 5, 5 ], [ 10 ] ]

Upvotes: 1

ttquang1063750
ttquang1063750

Reputation: 863

Use reduce

const matchesValues = ( array ) => {
  return array.reduce((previousValue, currentValue, currentIndex) => {
    if (currentIndex === 0 || (array[currentIndex - 1] + currentValue) === 10) {
      previousValue.push(currentValue);
    }

    return previousValue;
  }, []);
};

console.log(matchesValues([2,8,5,5,5,6]));

Upvotes: 2

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