Find Two Sum Indices

Problem Description: Given an array of integers and a target sum, find two distinct indices \(i\) and \(j\) such that \(arr[i] + arr[j] = target\). If such a pair exists, output the two indices (0-indexed) separated by a space. If there are multiple answers, output the first valid pair found. If no such pair exists, output "None".

Constraints: The array length can be large (up to \(10^5\) elements), so an efficient solution is required.

inputFormat

Input Format:

• The first line contains an integer \(n\), the number of elements in the array.
• The second line contains \(n\) space-separated integers representing the array elements.
• The third line contains an integer \(target\), the target sum.

outputFormat

Output Format:

• If a valid pair is found, output the two indices (0-indexed) separated by a space.
• If no such pair exists, output "None".

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2 7 11 15
9

0 1