<pre><code class="language-javascript">
/**
 * @param {number[][]} arrList
 * non-descending integer array
 * @return {number[]} 
 */
const sortByAsc = (a,b) =&gt; a - b;
function merge(arrList = []) {
  // bf
  // 1. merge all of them 
  // 2. sort by asc
  // const flattend = arrList.reduce((flattend, array) =&gt; {
  //   return flattend.concat(array);
  // }, []);
  // return flattend.sort(sortByAsc);

  // merged two sorted arrays
  const mergeSortedArrays = (arrayA, arrayB) =&gt; {
    const merged = [];

    while (arrayA.length &amp;&amp; arrayB.length) {
      const eleA = arrayA[0];
      const eleB = arrayB[0];

      if (eleA &lt; eleB) {
        merged.push(arrayA.shift());
      } else {
        merged.push(arrayB.shift());
      }
    }

    // either arrayA or arrayB can have reminders
    if (arrayA.length) {
      merged.push(...arrayA);
    }
    if (arrayB.length) {
      merged.push(...arrayB);
    }

    return merged;
  }

  let merged = []
  for (const array of arrList) {
    merged = mergeSortedArrays(merged, array);
  }

  return merged;
}
</code></pre>


This is my accepted solution

You are given a list of sorted non-descending integer arrays, write a function to merge them into one sorted non-descending array. merge( [ [1,1,1,100…

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