/*
 */

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

#define MAXPILES 10

int pile[MAXPILES];
int npiles;

extern void choosepiles();
extern int isover();
extern void usermove();
extern void computermove();
extern int randint(int from, int to);  /* inclusive */


int main()
{
    choosepiles();
    while (!isover()) {
	usermove();
	if (isover()) {
	    printf("you win! You must have cheated.\n");
	    break;
	}
	computermove();
	if (isover()) {
	    printf("I won! Despite your cheating.\n");
	    break;
	}
    }
    return 0;
}


void choosepiles()
{
    int i;
    npiles = randint(0, MAXPILES);
    for (i = 0; i < npiles; i++)
	pile[i] = randint(1, 10);
}


int isover()
{
    int i;
    for (i = 0; i < npiles; i++)
	if (pile[i])
	    return 0;
    return 1;
}


void usermove()
{
    int i, userpile, usersticks;
    char buf[100];
    do {
	printf("Choose a number of sticks and a pile to take them from:\n");
	for (i = 0; i < npiles; i++)
	    printf("pile %d has %d sticks.\n", i, pile[i]);
	printf("Pick a pile.\n");
	fgets(buf, 100, stdin);
	if (sscanf(buf, "%d", &userpile) != 1)
	    userpile = -1;  /* go around the loop */
    } while (userpile < 0 || userpile >= npiles || !pile[userpile]);
    do {
	printf("How many sticks from pile %d (out of %d)?\n", userpile,
		pile[userpile]);
	scanf("%d", &usersticks);
    } while (usersticks < 0 || usersticks > pile[userpile]);

    pile[userpile] -= usersticks;
}


void computermove()  /* precondition: the game is not over */
{
    int extrabits = 0;
    int mypile, mysticks;
    int i;

    for (i = 0; i < npiles; i++)
	extrabits = extrabits ^ pile[i];
    if (extrabits == 0) {
	for (i = 0; i < npiles; i++) {
	    if (pile[i]) {
		mypile = i;
		mysticks = 1;
	    }
	}
    } else {
	for (i = 0; i < npiles; i++) {
	    if ((pile[i] ^ extrabits) < pile[i]) {
		mypile = i;
		mysticks = pile[i] - (pile[i] ^ extrabits);
	    }
	}
    }
    printf("I take %d sticks from pile %d.\n", mysticks, mypile);
    pile[mypile] -= mysticks;
}


int randint(int from, int to)  /* inclusive */
{
    return rand() % (to - from + 1) + from;
}