Remove Duplicate Characters from a String

Code

#include <stdio.h>
#include <stdint.h>

void remove_duplicates(char *str) {
	int alfa[26]={0};
    int i=0,j=0;
    char cstr[100];
    do
    {
        alfa[str[j]-97]+=1;
       // printf("alf:%c--%d\n",*str,alfa[*str-97]);
        if(alfa[str[j]-97]==1)
        {
            str[i]=str[j];    
            i++;
        }
        else if(str[j]==' ')
        {
            str[i]=str[j];    
            i++;
        }
        j++;
    }while(str[j]!='\0');
    str[i]='\0';
    }

int main() {
    char str[101];
    fgets(str, sizeof(str), stdin);

    // Remove newline
    uint8_t i = 0;
    while (str[i]) {
        if (str[i] == '\n') {
            str[i] = '\0';
            break;
        }
        i++;
    }

    remove_duplicates(str);
    printf("%s", str);
    return 0;
}

Solving Approach