fastest program to check whether a number has duplicate digits or not?????

I need a fastest code that will tell me whether a number has duplicate digits or not…I don’t wanna use brute force technique coz that I have already tried.
Plz help

you can maintain an array of size 10…and each index represent a digit…to cater multiple occurrences of zero you can take the input as a string…after going through all the digits, if array[i] is greater than one then the digit has duplicate digit present else not…

int arr[10]={0};
input string;
len=legth of string;
while(i &lt len)
for(i=0;i &lt 10;i++)
{ if(arr[i]&gt 1)
  "Duplicate exists"
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