#include <stdio.h>
#include <math.h>
// Function to check if a number is prime
int isPrime(int n) {
if (n < 2) return 0;
if (n % 2 == 0) return n == 2;
int limit = (int)sqrt((double)n);
for (int i = 3; i <= limit; i += 2) {
if (n % i == 0) return 0;
}
return 1;
}
// Function to check if all digits are unique
int hasUniqueDigits(int n) {
int seen[10] = {0}; // track digits 0–9
while (n > 0) {
int d = n % 10;
if (seen[d]) return 0; // duplicate found
seen[d] = 1;
n /= 10;
}
return 1;
}
int main(void) {
for (int num = 1000; num <= 9999; num++) {
if (isPrime(num) && hasUniqueDigits(num)) {
printf("First 4-digit prime with all unique digits: %d\n", num);
return 0; // stop after finding the first one
}
}
printf("No such number found.\n");
return 0;
}
/*
run:
First 4-digit prime with all unique digits: 1039
*/
