Interview Questions/Coding/Count Target Pairs

Count Target Pairs

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Medium

Count Target Pairs

Count the number of distinct index pairs (i, j) such that: You are given an integer array nums and an integer target. 0 ≤ i < j < n nums[i] + nums[j] = target Return the total number of such pairs. Input Format- First line contains an integer n, the size of the array. Second line contains n space-separated integers representing nums. Third line contains an integer target. Output Format- Print the number of valid pairs.

Examples

Example 1

Input:

4
2 7 11 15
9

Output
1

Explanation
Only pair (0,1) has sum equal to 9.

Output:

Explanation: Only pair (0,1) has sum equal to 9.

Approach hint

Try checking every pair of indices.

Common mistake

Skipping assumptions, edge cases, or trade-offs can make an otherwise good answer feel incomplete.

solution.cpp