View Code of Problem 3924

#include<iostream>
#include<string.h>
using namespace std;
int main()
{
	char c[100000];
	int a[123]={0};//整体全部赋值 
	cin>>c;
	int len=strlen(c);
	for(int i=0;i<len;i++)
	{
		if(a[c[i]]==0) 
		{
			cout<<c[i];
		}
		a[c[i]]++; 
	}
  
  
}