sumZero.js

/*
Write a function called sumZero which accepts a sorted array of integers. The function should find the first pair where the sum is 0. Return an array that includes both values that sum to zero or undefined if a pair does not exist

sumZero([-3,-2,-1,0,1,2,3]) // [-3,3]
sumZero([-2,0,1,3]) // undefined
sumZero([1,2,3]) // undefined

*/

//brute force

function sumZero(arr) {
  if (arr.length >= 2) {
    for (let i = 0; i < arr.length; i++) {
      const current = arr[i];
      const opposite = -current;

      if (arr.includes(opposite)) {
        return [current, opposite];
      }
    }
  }
  return undefined;
}

function sumZero(arr) {
  for (let i = 0; i < arr.length; i++) {
    for (let j = i + 1; j < arr.length; j++) {
      if (arr[i] + arr[i] === 0) {
        return [arr[i], arr[j]];
      }
    }
  }
}

//refactored

function sumZero(arr){
    let left = 0;
    let right = arr.length - 1;
    while(left < right){
        let sum = arr[left] + arr[right]

        if(sum === 0){
            return [arr[left], arr[right]]
        }else if(sum > 0){
            right--
        }else{
            left++
        }
    }
}
sumZero([-4,-3,-2,-1,0,1,2,3,10])