<?php
$arr=array("viens","divi","viens","tris","cetri","divi","pieci");
$arr2=array();
foreach($arr as $val) $arr2[$val]=1;
foreach($arr2 as $key => $val) echo $key." ";
echo "\n";
$arr3=array_flip($arr);
foreach($arr3 as $key => $val) echo $key." ";