In this **HackerRank Lonely Integer - Bash! problem solution** There are N integers in an array A. All but one integer occur in pairs. Your task is to find the number that occurs only once.

**Input Format**

The first line of the input contains an integer N, indicating the number of integers. The next line contains N space-separated integers that form the array A.

**Constraints**

1 <= N < 100

N % 2 = 1 (N is an odd number)

0 <= A[i] <= 100, relate to [1,N]

**Output Format**

Output S, the number that occurs only once.

## Problem solution.

tail -n 1 | awk '{split($0, r, " "); t=0; for (i in r) t=xor(t, r[i]); print t;}'

## Second solution.

read N read -a A x=0 for i in "${A[@]}" do let " x ^= $i " done echo $x

## Third solution.

#!/bin/bash read n read -a arr x=${arr[0]}; for ((i=1;i<${#arr[@]};i++)) do x=$(($x ^ ${arr[$i]})); done echo $x;

## Fourth solution.

read x M=0 read r for N in $r do M=$(($N ^ $M)) done echo $M

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