Construct an array from its pair-sum array

Construct an array from its pair-sum array is a DSA topic. In plain words you use it for a short Construct an array from its pair-sum array example in a short dry-run on paper. Don’t start with a slogan — start with that picture.

Smallest example: the smallest Construct an array from its pair-sum array example you can type. Type it, run it, and say what you see. If you can do that from memory, you know Construct an array from its pair-sum array.

From the example next to this theory: Construct an array from its pair-sum array — arrays give O(1) index access; matrices are arrays of arrays.

Trap: only saying “Construct an array from its pair-sum array” with no example. Fix that before you talk about advanced DSA.

Viva: what is Construct an array from its pair-sum array? Then show the smallest Construct an array from its pair-sum array example you can type. Then name the trap.

Diagram

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

Exam tip

What is Construct an array from its pair-sum array? Show this: the smallest Construct an array from its pair-sum array example you can type. Trap: only saying “Construct an array from its pair-sum array” with no example.

Example

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

Construct an array from its pair-sum array — arrays give O(1) index access; matrices are arrays of arrays.

Short notes

DefConstruct an array from its pair-sum array — a short Construct an array from its pair-sum array example in a short dry-run on paper.
Rulethe smallest Construct an array from its pair-sum array example you can type
Traponly saying “Construct an array from its pair-sum array” with no example
Usea short dry-run on paper

Construct an array from its pair-sum array

From the example next to this theory: Construct an array from its pair-sum array — arrays give O(1) index access; matrices are arrays of arrays.

Trap: only saying “Construct an array from its pair-sum array” with no example. Fix that before you talk about advanced DSA.

Viva: what is Construct an array from its pair-sum array? Then show the smallest Construct an array from its pair-sum array example you can type. Then name the trap.

Diagram

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

Exam tip

Example

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

Construct an array from its pair-sum array — arrays give O(1) index access; matrices are arrays of arrays.

Short notes

DefConstruct an array from its pair-sum array — a short Construct an array from its pair-sum array example in a short dry-run on paper.
Rulethe smallest Construct an array from its pair-sum array example you can type
Traponly saying “Construct an array from its pair-sum array” with no example
Usea short dry-run on paper

Construct an array from its pair-sum array

Example

Short notes

Questions

Construct an array from its pair-sum array

Example

Short notes

Questions