#include <stdio.h>
#include <stdlib.h>
#include <time.h>
 
// Generate a random number not in the range [lo, hi)
int rand_outside(int lo, int hi) {
	int rangesize = hi - lo;
	int r = rand() % (RAND_MAX - rangesize + 1);
	if (r >= lo) r += rangesize;
	return r;
}
 
int main(void) {
	srand(time(NULL));
	int third = RAND_MAX / 3;
	int two_thirds = RAND_MAX - third + 1;
	int nbottom = 0, ntop = 0, nmiddle = 0;
	for (int i = 0; i < 10000; ++i) {
		// Get a random number in the bottom third or top third of the possibilities
		int r = rand_outside(third, two_thirds);
		if (r < third) ++nbottom;
		else if (r >= two_thirds) ++ntop;
		else ++nmiddle;
	}
	printf("In range [%10d, %10d]: %4d\n", 0, third - 1, nbottom);
	printf("In range [%10d, %10d]: %4d\n", third, two_thirds - 1, nmiddle);
	printf("In range [%10d, %10d]: %4d\n", two_thirds, RAND_MAX, ntop);
	return 0;
}
 

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