Check if two strings are permutation of each other | C ++ 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
bool arePermutation ( string str1 , string str2 ) { int count [ NO_OF_CHARS ] = { 0 } ; 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 ] ) return false ; return true ; }