Question

How to get array elements that appear more than once in C

Answer 1

#include <stdio.h>
#include <stdlib.h>
 
void getMoreThanOnce(int arr[], int len, int freq[]) {
   for (int i = 0; i < len; i++) {
         freq[arr[i]]++;
   }
}
  
int main() {
    int arr[] = {1, 6, 3, 1, 8, 9, 9, 1, 3, 4};
  
    int len = sizeof(arr)/sizeof(arr[0]);
    int *freq = (int *)calloc(sizeof(int), 10);
     
    getMoreThanOnce(arr, len, freq);
     
    for (int i = 0; i < 10; i++) {
      if (freq[i] > 1)
         printf("%3d", i);
    }
    
   free(freq);
}
 
 
 
/*
run:
 
1  3  9
   
*/

 

70+ SQL courses for beginners and professionals