Two Sum Problem (Standard I/O Version)

You are given an array of integers and a target integer. Your task is to find the indices of the two numbers in the array such that they add up to the target. If there exists such a pair, output the two indices separated by a space. Otherwise, output [] to indicate that no valid pair exists.

Note: There is exactly one solution in the original problem statement, but in this version, there might be no solution. Use an efficient algorithm to achieve a time complexity close to \(O(n)\).

Examples:

• Input: 4\n2 7 11 15\n9 — Output: 0 1
• Input: 4\n1 2 3 4\n10 — Output: []

inputFormat

The input is read from standard input (stdin) and has the following 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

The output should be written to standard output (stdout). If there exists a pair of indices \(i\) and \(j\) (with \(i < j\)) such that the sum \(nums[i] + nums[j] = target\), print the indices separated by a single space. If no such pair exists, print [].

4
2 7 11 15
9

0 1