Remove from Destination array all occurrences of all characters that occur in Source Array [closed]
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Given two character arrays a[] and b[], remove from b[] all occurrences of all characters that occur in array a[]. You need to do this in-place i.e. without using an extra array of characters. E.g.:
Input: a[] = [‘G’, ‘O’]
Input b[] = [‘G’, ’O’, ’O’, ’G’, ’L’, ’E’]
Output: b[] = [‘L’, ‘E’]
Code :
public class ReplaceCharacterArray{
public static void main(String args[]){
char a[] = [‘G’, ‘O’]
char b[] = [‘G’, ’O’, ’O’, ’G’, ’L’, ’E’]
//to replace all the occurences of all the characters of
//a[] array in b[] array we have below logic.
for(int i=0;i<a.length;i++){
for(int j=0;j<b.length;j++){
if(b[j] == a[i]){
//im stuck here how to proceed
}
}
You can't remove elements "in place" in Java arrays. They have fixed length. That is, in your example you'll have to return a new array, since you can't change the length of the b
array.
Here are some pointers for you:
- Maintain a write-index for the
b
array (left of this index, you have only characters not present ina
). - Iterate through the
b
array - While the current character is contained in
a
, step forward - Swap current character (not contained in
a
) with the character at the write-index - Increment the write-index, and continue from there.
Use for instance Arrays.copyOfRange
to return the part of the array to the left of the write-index.
Regarding your update:
- Arrays are not written using
[
and]
and characters are not written using‘
, change them to{
,}
and'
. - Having a helper method with the signature
boolean arrayContains(char[] arr, char c)
will make it easier to write the algorithm - If you follow my approach, you will also benefit from having a helper method
void swap(char[] arr, int index1, int index2)
.
You can go about like this
Iterate the loop a, that is 2 times and In each iteration, perform the copare that value exists in the b[] array, if yes delete that. Continue that until you iterate the array b[] completely.
So that in the end you will have b[] array only with the other elements which is not in the array a[].
I hope this will help you to complete your work.
I guess since this is a homework 3rd party library's may not be allowed.Any way i'll just post a code using Guava:
char[] removeChars(char a[],char b[])
{
return CharMatcher.anyOf(new String(b)).removeFrom(new String(a)).toCharArray();
}
UPDATE:(check this sample,it's one way to solve)
import java.util.*;
import java.lang.*;
class CharReplace{
public static void main(String[] args)
{
char a[] = "GOOGLE".toCharArray();
char b[] = "GO".toCharArray();
BitSet charToRemove=new BitSet();
for(char c:b)
charToRemove.set(c);
StringBuilder str=new StringBuilder();
for(char c:a)
if(!charToRemove.get(c))
str.append(c);
b=str.toString().toCharArray();
System.out.println(Arrays.toString(b));
}
}
You have mistakes in your code,
- Arrays don't start and end with
[
and]
respectively. They start and end with{
and}
respectively. - Characters are enclosed with
'
only. - You will have to keep the state of your iterations (in my case I kept the indexing state and the state of to know whether the character in
b
exists ina
). - Have a
remove(char[] array, char characterToRemove)
and pass theb[]
and it's respective character to remove to complete the flow.
Update without using String
, StringBuffer
, or any libraries, this is what works....
Warning the array b
never gets reduced (it gets appended with NULL
character). That I will leave it for you to crack.
/**
* @author The Elite Gentleman
*
*/
public class ReplaceCharacterArray {
public static boolean containsCharacter(char character, char[] array) {
for (int i = 0; i < array.length; i++) {
if (array[i] == character) {
return true;
}
}
return false;
}
/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
char a[] = {'G', 'O'};
char b[] = {'G', 'O', 'O', 'G', 'L', 'E'};
//to replace all the occurences of all the characters of a[] array in b[] array we have below logic.
int index = 0;
int count = 0;
while (index < b.length) {
while (ReplaceCharacterArray.containsCharacter(b[index], a)) {
System.arraycopy(b, index + 1, b, 0, b.length - index - 1);
count++;
}
index++;
}
for (int i = (b.length - count); i < b.length; i++) {
b[i]= '\0';
}
for (int i = 0; i < b.length; i++) {
System.out.println(b[i]);
}
}
}
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