The Runtime Theory
easyLeetCode#two-pointers#in-place

Merge Sorted Array

Merge two sorted arrays into the first array, which has enough trailing capacity.

The Runtime Theory Team25 min read
Solve it

Solving happens on the judge — come back and mark it done

Sample cases

innums1=[1,2,3,0,0,0], m=3, nums2=[2,5,6], n=3

out[1,2,2,3,5,6]

innums1=[1], m=1, nums2=[], n=0

out[1]

innums1=[0], m=0, nums2=[1], n=1

out[1]

Merge two sorted arrays into the first array, which has enough trailing capacity.

A good solution should

  • State the invariant or decision rule that makes the approach correct.
  • Explain time and space costs in terms of input size and required output.
  • Handle empty, minimal, duplicate, and boundary-shaped inputs.

Reasoning prompt

Fill from the end so unread values in the first array are not overwritten.

Use the linked judge for the canonical challenge. The examples above are compact TRT checks; create additional tests around the boundary most likely to break your invariant.

More practice in this topic

easy · arraysContains Duplicatemedium · arraysEncode and Decode a List of Stringsmedium · arraysGroup Anagrams

One dispatch a week

The trace behind each problem, the tradeoff that explains it, and one technical dispatch per week — no noise.

One technical dispatch per week. No noise.

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