CareerCup

<pre lang="c" line="1" title="CodeMonkey31292" class="run-this">#include <stdio.h>

void RemoveCharacters(char[], char[]);

int main(void) {
char input[] = "This program removes specified characters from a string";
char remove[] = "aeiou";
RemoveCharacters(input, remove);
return 0;
}

void RemoveCharacters(char input[], char* remove)
{
int i = 0;
char bitmap[256] = {NULL};

while(remove[i])
{
bitmap[remove[i]] = 1;
i++;
}

int write = 0, curr = 0;

while(input[curr])
{
if(!bitmap[input[curr]])
{
input[write] = input[curr];
write++;
}
curr++;
}
input[write] = NULL;

printf("%s", input);
}
</pre><pre title="CodeMonkey31292" input="yes">
</pre>

Since there is no restriction to use string class function, strtok() can be used.
But if not then do (crude method)

F(char* iStr, char* List)
   {
       int i = strlen(iStr); 
       int j = 0 ;
       for( k = 0 ; k < strlen(List) ; k++)    
       for( j = 0 ; j < i ; j++)
          if(iStr[j] == List[k])
          {
            iStr[j] = iStr[j+1];
            iStr[j+1] = ' ';
            j += 1;  
          }
   }
   Complexity O(strlen(List) * strlen(iStr))

string removechar(string in, string remove)
{
	int i=0;
	int asciiarray[256];
	string temp;

	for (i=0; i<256; i++)
		asciiarray[i] = 0;

	for (i=0; i<remove.size(); i++)
		asciiarray[remove[i]]++;

	for (i=0; i<in.size(); i++)
		if (asciiarray[in[i]] < 1)
			temp = temp + in[i];
	
	return temp;
}

Sort the list of input characters that need to be deleted. and then binary search each char in the input string.
Say if
m = length of the list of characters to be deleted.
n = number of characters in original list.

Step 1) O( nlog(m) ) for sorting
Step 2) O ( n * log(m) ) for search

Overall : O( n log (m) )

1) Store the Input string characters in a Linked List.
2) Loop through the array of deletion chars and for those chars remove the corresponding nodes from the linked list.
3) Store the resultant linked list into another array.
4) Reverse the resultant array using swapping algorithm

Store the chars to be deleted in a Hash Map. Initialize the counter i,j=0;
i: Loop though the i/p string.

If the char exists in the Hash Map, increment i
If the char does not exist in the Hash Map copy arr[j]= arr[i]; increment i,j

Put a '\0'at the jth location of the i/p string

For reversing the normal recursive code

void charDelete(){
	char A[]="ithss is nice  this is a very nice";
	char B[]="aeiou";
	char* delp=B;
	char* start=A;
	char* end=A;

	while(1){
		delp=B;
		while(*delp){
			if(*delp==*start){
				start++;
				*end=*start;//'$';
				delp=B;
			}
			delp++;
		}
		*end++=*start++;
		 		
		if(!*end){
			break;
		}	
	}
	
	cout << A;

};