Bucket sorting in C language

        When we're dealing with it c When de duplication of super large data in language , The running efficiency of the program will be very low , The running memory will be very large .

        Such as this topic , The background gives a huge amount of data , If we write ordinary counting and sorting functions, we will not be able to process these data , So we need to find a stronger idea .

        Our normal method is , Create an array , Store every element , But this will cause the array to be very large . So we changed our mind , Use subscripts to store data , Let the element content store the number of occurrences of this small mark , It's easy to solve . The code is as follows .

#define _CRT_SECURE_NO_WARNINGS 1
#include <stdio.h>
#define NUM 500000


int main()
{
	int arr[NUM] = { 0 };
	int num = 0;
	int tmp = 0;
	scanf("%d", &num);
	for (; num >0; num--)
	{
		tmp = 0;
		scanf("%d", &tmp);
		arr[tmp]++;
	}
	for (num = 0; num < NUM; num++)
	{
		if (arr[num] != 0)
			printf("%d ", num);
	}
	return 0;
}