#include <stdlib.h>
#include <stdarg.h>

#define BALL_N 12
#define NORMAL_WEIGHT 10
#define MAX_WEIGHS 3

static int balls[BALL_N + 1]; /* ball weights */
static int weight_c = 0; /* number of weighs performed */

/* positions of each ball for each weight, position 0 is not used */
static char weigh1_positions[] = " L--LLRR--LRR";
static char weigh2_positions[] = " -L---LRLRRLR";
static char weigh3_positions[] = " --RLR--RRLLL";

/* returns: <0 if right heavier, 0 if equal, >0 if left heaver */
static int weigh(const char *positions)
{
int ball_c, ball, total = 0;

weight_c++;
if (weight_c > MAX_WEIGHS) abort();

for (ball_c = 1; ball_c <= BALL_N; ball_c++) {
if (positions[ball_c] == 'L') {
total += balls[ball_c];
}
else if (positions[ball_c] == 'R') {
total -= balls[ball_c];
}
}

return total;
}

/*
* Do the 3 weighs and then figure out which ball is different. It
* will return the number of the ball as a negative number if it is
* lighter than the others or a position value if it is heavier.
*/
int do_it(void)
{
int ball_c, weigh1, weigh2, weigh3;

weigh1 = weigh(weigh1_positions);
weigh2 = weigh(weigh2_positions);
weigh3 = weigh(weigh3_positions);

/* check for heavier */
for (ball_c = 1; ball_c <= BALL_N; ball_c++) {
switch (weigh1_positions[ball_c]) {
case 'L': if (weigh1 <= 0) continue; break;
case 'R': if (weigh1 >= 0) continue; break;
case '-': if (weigh1 != 0) continue; break;
}
switch (weigh2_positions[ball_c]) {
case 'L': if (weigh2 <= 0) continue; break;
case 'R': if (weigh2 >= 0) continue; break;
case '-': if (weigh2 != 0) continue; break;
}
switch (weigh3_positions[ball_c]) {
case 'L': if (weigh3 <= 0) continue; break;
case 'R': if (weigh3 >= 0) continue; break;
case '-': if (weigh3 != 0) continue; break;
}
return ball_c;
}

/* check for lighter */
for (ball_c = 1; ball_c <= BALL_N; ball_c++) {
switch (weigh1_positions[ball_c]) {
case 'L': if (weigh1 >= 0) continue; break;
case 'R': if (weigh1 <= 0) continue; break;
case '-': if (weigh1 != 0) continue; break;
}
switch (weigh2_positions[ball_c]) {
case 'L': if (weigh2 >= 0) continue; break;
case 'R': if (weigh2 <= 0) continue; break;
case '-': if (weigh2 != 0) continue; break;
}
switch (weigh3_positions[ball_c]) {
case 'L': if (weigh3 >= 0) continue; break;
case 'R': if (weigh3 <= 0) continue; break;
case '-': if (weigh3 != 0) continue; break;
}
return -ball_c;
}

abort();
}

int main()
{
int diff_c, ball_c;

/* init all of the balls */
for (ball_c = 1; ball_c <= BALL_N; ball_c++)
balls[ball_c] = NORMAL_WEIGHT;

for (diff_c = 1; diff_c <= BALL_N; diff_c++) {
(void)printf("Odd is %2d: ", diff_c);

weight_c = 0;
balls[diff_c] = NORMAL_WEIGHT - 1;
if (do_it() != -diff_c) abort();
(void)printf("lighter, ");

weight_c = 0;
balls[diff_c] = NORMAL_WEIGHT + 1;
if (do_it() != diff_c) abort();
(void)printf("heaviern");

balls[diff_c] = NORMAL_WEIGHT;
}
return 0;
}
/* end of program */