Question

How to generate 100 <x,y> random points on a circle and display them in C

Answer 1

#include <stdio.h>
#include <stdlib.h>
#include <time.h>

// 10 >= sqrt(x**2 + y**2) <= 15

int _random(int n) {
	int rand_max = RAND_MAX - (RAND_MAX % n);
	int rnd;
	while ((rnd = rand()) > rand_max);
	
	return rnd / (rand_max / n);
}

int main()
{
	unsigned long arr[31] = {0}; 

	srand(time(NULL));
	
	for (int i = 0; i < 100; ) {
		int x = _random(31) - 15;
		int y = _random(31) - 15;
		int border = x * x + y * y;
		if (border >= 100 && border <= 225) {
			arr[15 + y] |= 1 << (x + 15);
			i++;
		}
	}

	for (int i = 0; i < 31; i++) {
		for (int j = 0; j < 31; j++)
			printf((arr[i] & 1 << j) ? ". " : "  ");
		printf("\n");
	}

	return 0;
}



/*
run:

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*/

 

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