Key Matching using shell

Question

I wanted to see different type of answers I receive from you guys for the below problem. I am curious to see below problem being solved completely through array or any other

Answer 1

With bash and sort:

#!/bin/bash

declare -A array         # define associative array

# read file input.txt to array
while IFS=", " read -r line number; do
  array["$line"]+=",$number"
done < input.txt

# print array
for i in "${!array[@]}"; do
  echo "$i${array[$i]}"
done | sort 

Output:

Name1,Phone1,Phone2
Name2,Phone2,Phone1
Name3,Phone1
Name4,Phone5,Phone1