finding the sum of two arrays elements that is equal to the input

debugcn Published at Dev

LorenzoDev

trying to iterate over an array to find two array items whose sum equals the target, not sure why isnt working

const numsArr = [2,7,11,15]
const numTarget = 9

const  twoSum = function(nums, target) {
    const first = 0;
    const second = 0;
    for(i=0; i<=nums.length; i++){
        let tester = nums[i];
        if(tester + nums[i] == target){
          console.log('found it ')
            
            
        }else{
          console.log('i failed')
        }
    }
};
twoSum(numsArr, numsTarget)

KooiInc

You should always check for typo's: numTarget is not numsTarget; Furthermore, break the loop if the desired result is reached. Try something like:

const numsArr = [2, 7, 11, 15];

const sumFromTarget = (nums, target) => {
  let sum = 0;
  
  for (let i = 0; i <= nums.length; i += 1) {
    sum += nums[i];
    //  ^ add current value to sum
    if (sum === target) {
      console.log(nums.slice(0, i + 1).join(" + ") + " = " + target);
      break;
      // result is reached, no need for further processing
    } 
  }
  
  if (sum !== target) {
  //  ^ true if the loop is completed without result
    console.log(`Could not reach ${
      target} summing the consecutive values of the given array`);
  }
}

sumFromTarget(numsArr, 9);
sumFromTarget(numsArr, 17);
sumFromTarget(numsArr, 20);

Now if you want to find a certain sum from any of the values in the array, you have to do a bit more work. Something like:

console.clear();
const numsArr = [2, 7, 11, 15];

const sumFromTarget = (nums, target) => {
  let nums2 = nums.slice();
  let resultValues = [];

  for (let i = 0; i <= nums.length; i += 1) {
    const x = nums2.reduce((acc, n, ni) => {
      const runningTotal = ni > 0 ? acc[ni - 1][1] + n : n;
      
      if (runningTotal === target) {
        resultValues = nums2.slice(0, ni + 1);
      }
      
      if (n + nums[i] === target) {
        resultValues = [nums[i], n];
      }
      
      return [...acc, [n + nums[i], runningTotal]];
    }, []);

    const check = x.find(n => n[0] === target || n[1] === target);

    if (check) {
      console.log(`found a solution (${resultValues.join(" + ")})`);
      sum = target;
      break;
    }
  }

  if (!resultValues.length) {
    console.log(`Could not reach ${
      target} summing any of the values of the given array`);
  }
}

sumFromTarget(numsArr, 9);
sumFromTarget(numsArr, 17);
sumFromTarget(numsArr, 13);
sumFromTarget(numsArr, 120);

Collected from the Internet

Please contact [email protected] to delete if infringement.