DSA · Theory

Sort an almost sorted array

Theory

541/810

Sort an almost sorted array is a DSA idea you prove with names A→Z, not with a slogan.

Sort an almost sorted array order — meaning → n log n vs n² → one limit. Dumping ten features helps nobody.

Skip Sort an almost sorted array and unstable sort when equal keys matter shows up in the roll list.

Use Sort an almost sorted array when names A→Z must stay clear. If a simpler DSA step works, use that instead.

Don’t do this with Sort an almost sorted array: unstable sort when equal keys matter. Interviewers spot it in ten seconds.

Sort an almost sorted array is not a lonely heading. Arun ties it to names A→Z.

Close Sort an almost sorted array with: “If I skip it, names A→Z goes wrong like this: unstable sort when equal keys matter.”

Diagram

  index →  0    1    2
  array → [10,  20,  30]

Exam tip

Board: names A→Z. Dry-run Sort an almost sorted array. Name the trap: unstable sort when equal keys matter.

arr = [10, 20, 30, 40]
print(arr[2], arr[-1])
matrix = [[1, 2], [3, 4]]
print(matrix[1][0])  # 3

Sort an almost sorted array — arrays give O(1) index access; matrices are arrays of arrays.