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This is a hard difficulty Coding & Algorithms question, commonly asked during Take-home Project rounds at Capital One.

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This question is commonly asked for Machine Learning Engineer candidates at Capital One during technical interviews.

Support updates and count target-sum pairs | Capital One Interview Question

Q: Support updates and count target-sum pairs

This question evaluates data structures and algorithmic skills for dynamic pair counting, focusing on frequency management, efficient update handling, and query-time computation in a two-sum variant.

You are given two integer arrays:

A (fixed / primary)
B (modifiable / secondary)

You must process a sequence of operations of two types:

Update : set B[index] = value .
Query : given an integer target , return the number of pairs (i, j) such that A[i] + B[j] == target .

Pairs are counted with multiplicity: if A contains duplicates or B contains duplicates, each index combination counts as a distinct pair.

Input

Arrays A and B
A list of operations, each operation is either:
- ("update", index, value)
- ("count", target)

Output

For each ("count", target) operation, output an integer: the number of valid pairs.

Example

A = [1, 2, 2]
B = [3, 2]
Query target = 4
- Valid pairs are (1,3) , (2,2) using the first 2 in A , and (2,2) using the second 2 in A → total 3 .

Constraints (assume typical interview constraints)

1 <= len(A), len(B) <= 10^5
Number of operations up to 10^5
Values can be negative and up to typical 32-bit integer range.

You are given two integer arrays:

A (fixed / primary)
B (modifiable / secondary)

You must process a sequence of operations of two types:

Update : set B[index] = value .
Query : given an integer target , return the number of pairs (i, j) such that A[i] + B[j] == target .

Pairs are counted with multiplicity: if A contains duplicates or B contains duplicates, each index combination counts as a distinct pair.

Input

Arrays A and B
A list of operations, each operation is either:
- ("update", index, value)
- ("count", target)

Output

For each ("count", target) operation, output an integer: the number of valid pairs.

Example

A = [1, 2, 2]
B = [3, 2]
Query target = 4
- Valid pairs are (1,3) , (2,2) using the first 2 in A , and (2,2) using the second 2 in A → total 3 .

Constraints (assume typical interview constraints)

1 <= len(A), len(B) <= 10^5
Number of operations up to 10^5
Values can be negative and up to typical 32-bit integer range.

Support updates and count target-sum pairs

Quick Overview

Input

Output

Example

Constraints (assume typical interview constraints)

Comments (0)

Support updates and count target-sum pairs

Quick Overview

Input

Output

Example

Constraints (assume typical interview constraints)

Comments (0)