ewce09.azraftaohid.me/L2T1/CSE 278/Practices/w10/duplicates.c

#include <stdio.h>

int min(int a, int b) {
	return a < b ? a : b;
}

int max(int a, int b) {
	return a > b ? a : b;
}

/**
 * Checks if provided arr includes an element starting from {@param headStart}
 * position
 * 
 * @returns zero to indicate the element was not found, one to indicate found
 */
int arrContains(int element, int arr[], int arrLen, int headStart) {
	for (int i = headStart; i < arrLen; i++) {
		if (element == arr[i]) return 1;
	}

	return 0;
}

void arrFill(int filler, int arr[], int arrLen) {
	for (int i = 0; i < arrLen; i++) {
		arr[i] = filler;
	}
}

int main() {
	int arr[] = { 2, 4, 5, 1, 2, 8, 6, 6 };
	int size = sizeof(arr) / sizeof(int);

	// keep track of individual processed duplicates so that we won't account
	// for the same duplicate element twice
	int duplicates[size];
	int duplicateI = 0;
	arrFill(0, duplicates, size); // we can't have random values

	// notice that duplicate arr is filled with zeros, but original array
	// can also contain duplicates of zeros
	int zeroImpact = -1;
	for (int i = 0; i < size; i++) {
		int it = arr[i];

		if (it == 0) { // handle the case of zero separately
			zeroImpact++;
			continue;
		} else if (arrContains(it, duplicates, size, 0)) {
			continue; // value is already processed as duplicate
		}

		if (arrContains(it, arr, size, i + 1)) duplicates[duplicateI++] = it;
	}

	// if there are no duplicate of zeros, increment by 0; otherwise increment
	// by 1 at most
	printf("%d duplicates found.", duplicateI + max(0, min(1, zeroImpact)));
}