Check if two strings are permutation of each other | Java function to check whether two strings are Permutations of each other ; Create a count array and initialize all values as 0 ; For each character in input strings , increment count in the corresponding count array ; If both strings are of different length . Removing this condition will make the program fail for strings like " aaca " and " aca " ; See if there is any non - zero value in count array
static boolean arePermutation ( char str1 [ ] , char str2 [ ] ) { int count [ ] = new int [ NO_OF_CHARS ] ; int i ; for ( i = 0 ; str1 [ i ] && str2 [ i ] ; i ++ ) { count [ str1 [ i ] ] ++ ; count [ str2 [ i ] ] -- ; } if ( str1 [ i ] str2 [ i ] ) return false ; for ( i = 0 ; i < NO_OF_CHARS ; i ++ ) if ( count [ i ] != 0 ) return false ; return true ; }