Create DFA for all the String Combination of 0&1 which doesn’t allow Substring 110

#include<stdio.h>

#include<conio.h>

#include<string.h>

void main()

{

          char str[50];

          int i,len,flag;

          clrscr();

          printf("\n Enter the String:-");

          gets(str);

          len=strlen(str)-1;

          for(i=0;i<len;i++)

          {

                   if(str[i]=='1' && str[i+1]=='1' && str[i+2]=='0')

                             flag=1;

          }

          if(flag==1)

                   printf("\n INValidddd.....");

          else

                   printf("\n Valid String");

  getch();

}