How to get a contiguos subarray

getIntervals

const number = 4
const affected = [1, 2]
const poisonous = [3, 4]

function getSubArrayz(n) {
  const LEFT = [];
  let answer = 0

  for(let i = 0; i <= n; i++){
    LEFT[i] = 0;
  }

  console.log('LEFT 1', LEFT)

  for(let i = 0; i < poisonous.length; i++) {
    if(affected[i]) {
      let a = affected[i];
      let b = poisonous[i];
      let tmp;

      console.log('L B', a, b)

      if(a > b) {
        tmp = a;
        a = b;
        b = tmp;
      }

      LEFT[b] = Math.max(LEFT[b], a)
    }
  }

  console.log('LEFT 2', LEFT)

  for(let i = 2; i <= n; i++) {
    LEFT[i] = Math.max(LEFT[i], LEFT[i - 1]);
  }

  console.log('LEFT 3', LEFT)
  for(let i = 1; i <= n; i++) {
    answer += i - LEFT[i];
  }
  console.log('LEFT 4', LEFT)

  return answer;
}

getSubArrayz(number)