PROBLEM DESCRIPTION
Given a string str without spaces, the task is to remove all duplicate characters from it, keeping only the first occurrence.
Note: The original order of characters must be kept the same.
SOLUTION
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class Solution {
String removeDups(String str) {
int[] chars = new int[26];
StringBuffer sb = new StringBuffer();
for(int i=0; i<str.length(); i++){
char ch = str.charAt(i);
if(chars[ch - 'a'] == 0){
sb.append(ch + "");
chars[ch - 'a'] = 1;
}
}
return sb.toString();
}
}