Day 3: Mull It Over

Megathread guidelines

  • Keep top level comments as only solutions, if you want to say something other than a solution put it in a new post. (replies to comments can be whatever)
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FAQ

  • sjmulder@lemmy.sdf.org
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    8 days ago

    Got the code a little shorter:

    Code
    #include "common.h"
    
    static int
    parse_mul(const char **stringp, int *ap, int *bp)
    {
    	const char *cur = *stringp, *end;
    
    	if (strncmp(cur, "mul(", 4)) { return 0; } cur += 4;
    	*ap = (int)strtol(cur, (char **)&end, 10);
    	if (end == cur)  { return 0; } cur = end;
    	if (*cur != ',') { return 0; } cur += 1;
    	*bp = (int)strtol(cur, (char **)&end, 10);
    	if (end == cur)  { return 0; } cur = end;
    	if (*cur != ')') { return 0; } cur += 1;
    
    	*stringp = cur;
    	return 1;
    }
    
    int
    main(int argc, char **argv)
    {
    	static char buf[32*1024];
    	const char *p;
    	size_t nr;
    	int p1=0,p2=0, a,b, dont=0;
    
    	if (argc > 1)
    		DISCARD(freopen(argv[1], "r", stdin));
    
    	nr = fread(buf, 1, sizeof(buf), stdin);
    	assert(!ferror(stdin));
    	assert(nr != sizeof(buf));
    	buf[nr] = '\0';
    
    	for (p = buf; *p; )
    		if (parse_mul(&p, &a, &b)) { p1 += a*b; p2 += a*b*!dont; }
    		else if (!strncmp(p, "do()", 4))    { dont = 0; p += 4; }
    		else if (!strncmp(p, "don't()", 7)) { dont = 1; p += 7; }
    		else p++;
    
    	printf("03: %d %d\n", p1, p2);
    }