Remove duplicate characters from a string in O(N) time complexity

Remove duplicate characters from a string in O(N) time complexity

  January 16, 2017    

---

#include<iostream>
using namespace std;
int main()
{
char str[101];// max limit of a string is 100
cin>>str;
int i=0,j=0;
int a[257]={0};//we will use this for using hash function
while(str[i]!='\0')
{
if(a[str[i]]==1)
{
i++;
}
else
{
a[str[i]]=1;
str[j]=str[i];
i++;
j++;
}
}
str[j]='\0';
cout<<str;
return 0;
}