def bubble$\_$sort$($arr$)$:

n $=$ len$($arr$)$

for $i$ in range$($n$)$:

for $j$ in range $(,n-i-1)$ :

if arr$[j]>$arr$[j+1]$ :

arr$[j],$arr$[j+1]=$arr$[j+1],$arr$[j]$

Find the time complexity$($O$($n$))$ of the above code.