[pva]

Код:

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

int main() {
	int const x2=78, y2=30, pitch=x2+1, area_size=pitch*y2;
	
	int x=1, normal=(x2-y2)/2;
	char *img = malloc(area_size), *last=img+area_size-pitch, *row=last;
	
	memset(img, ' ', area_size);
	
	for(;;) {
		if (0<normal) {
			normal-=y2;
			img[x]=last[x]=row[x]='x';
			if (x<x2) { ++x; }
		}
		else {
			normal+=x2;
			row[0]=row[pitch-2]='x';
			row[pitch-1]='\n';
			if ((row-=pitch)<img) break;
		}
	}
	
	fwrite(img, y2, pitch, stdout);	
	free(img);
}

Код:

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

int main() {
	int const x2=78, y2=30, pitch=x2+1, area_size=pitch*y2;
	
	char *img = malloc(area_size);
	unsigned const dx=x2-2, dy=y2-2;
	int const width = (x2+y2)/2;
	unsigned x, y;
	for(y=0; y<y2; ++y) {
		img[(y+1)*pitch-1] = '\n';
		for(x=0; x<x2; ++x) {
			img[y*pitch+x] = 
				x - 1 < dx && y - 1 < dy &&
				width < (x-dx)*dy + y*dx ? ' ' : 'x';
		}
	}
	
	fwrite(img, y2, pitch, stdout);	
	free(img);
}