1	#include<stdio.h>
     2	//#define TRUE_RANDOM
     3	#define xor ^
     4	#define bool int
     5	#define  MIN_PILE  2
     6	#define  MAX_PILE  7
     7	#define  MIN_STONE 7
     8	#define  MAX_STONE 30
     9	int myrandom(int lower, int upper);
    10	void hello(), byebye();
    11	void playNIM();
    12	int main(){
    13	   static char yesNo[99];
    14	   hello();
    15	   while(38){
    16	      playNIM();
    17	      fprintf(stderr, "Play again (Y,N): ");
    18	      fgets(yesNo, 99, stdin);
    19	      if( toupper(yesNo[0]) == 'N') break;
    20	   }
    21	   byebye();
    22	}
    23	int nPile,takeP,takeN;
    24	int pile[MAX_PILE+2];
    25	int userFirst;
    26	int lastWin;
    27	char tmp99[99];
    28	void prepareStones();
    29	void tellStatus();
    30	bool gameOver();
    31	void userTurn();
    32	void computerTurn();
    33	void playNIM(){
    34	      static char yesNo[99];
    35	    prepareStones();
    36	    tellStatus();
    37	    fprintf(stderr, "take last one to ");
    38	    if(lastWin) fprintf(stderr, "Win!\n");
    39	    else fprintf(stderr, "Lose!\n");
    40	    userFirst = 1;
    41	    fprintf(stderr, "Want to go first(Y,N)? ");
    42	    fgets(yesNo, 99, stdin);
    43	    if( toupper(yesNo[0]) == 'N') userFirst = 0;
    44	    if(userFirst)
    45	        userTurn();
    46	    while(49){
    47	        if(gameOver()){   /* user takes the last one */
    48	            if(lastWin) printf("Congratulations! You win!\n");
    49	            else printf("Ahh Ha! I win!\n");
    50	            break;
    51	        }
    52	        computerTurn();
    53	        if(gameOver()){
    54	            if(lastWin) printf("Ahh Ha! I win!\n");
    55	            else printf("Congratulations! You win!\n");
    56	            break;
    57	        }
    58	        userTurn();
    59	    } /* while(49) */
    60	} /* playNIM */
    61	bool gameOver( ){
    62	     int i;
    63	   int sum = 0; 
    64	   for(i=1; i<= nPile; i++){
    65	       sum += pile[i];
    66	   }
    67	   return sum == 0;    /* no stones left */
    68	}
    69	  /*****************/
    70	void prepareStones(){
    71	    int i;
    72	    nPile = myrandom(MIN_PILE, MAX_PILE);
    73	    for(i=1; i<= nPile; ++i){
    74	        pile[i] = myrandom(MIN_STONE, MAX_STONE);
    75	    }
    76	    lastWin = 0;
    77	    if( myrandom(0, 100) > 50) lastWin = 1;
    78	   /***
    79	     sound(400);  delay(200);  nosound;
    80	      ***/
    81	}


    82	  /******/
    83	bool leagleMove(int p, int n){
    84	    if(p<1 || p > nPile) return 0;
    85	    if(n<1 || n > pile[p]) return 0;
    86	    return 1;
    87	}
    88	void tellStatus(){
    89	    int i, ktemp;
    90	    printf("There are %d piles of each has ", nPile);
    91	    for(i=1; i<= nPile; ++i){
    92	        printf( "  %d", pile[i]);
    93	    }
    94	    printf(" stones.\n");
    95	}
    96	void userTurn(){
    97	    /** make sure the player makes a legal move **/
    98	    int i, ktemp;
    99	    tellStatus();
   100	    do {
   101	        /** sound(400);  delay(200);  nosound;  /*** ***/
   102	       printf("Which Pile? ");
   103	       gets(tmp99); takeP = atoi(tmp99);
   104	       ktemp = 0; 
   105	       if(leagleMove(takeP, 1) ) ktemp= pile[takeP];
   106	       printf("How many stones in this pile?(1..%d) ", ktemp);
   107	       gets(tmp99); takeN = atoi(tmp99);
   108	    } while( ! leagleMove(takeP, takeN) );
   109	    pile[takeP] -=  takeN;
   110	    return;
   111	} /* userTurn */
   112	 /***************************/
   113	void computerTurn(){          /* try to win if possible */
   114	    int i;
   115	    takeN = pile[1];   /* assume All stones in 1st pile is OK */
   116	    /* first of all, calculate how many stones will the xor result be? */
   117	    for(i=2; i<= nPile; ++i) takeN = takeN ^ pile[i];   /* xor */
   118	    if( takeN == 0) {  /* I can Not win :-<  */
   119	        /* I am supposed to lose so far. So just take one stone. */
   120	        takeP = 1; takeN = pile[takeP];   /* takeN 暫時記住最多幾個stone */
   121	        for(i=2; i<=nPile; ++i){
   122	            if( pile[i] > takeN){
   123	               takeP=i;  takeN= pile[takeP];
   124	            }
   125	        }
   126	        takeN = 1;
   127	    }else{
   128	       /* now decide which pile we can remove some stones to win*/
   129	       for(i = nPile; i>=1; --i){
   130	           if ( (takeN xor pile[i]) < pile[i] ) takeP=i;
   131	       }
   132	       /* now calculate 真正該拿之石頭數 */
   133	       takeN = pile[takeP] - (pile[takeP] xor takeN);    /***重要***/
   134	    } /* if( takeN ==0 ... */
   135	    pile[takeP] = pile[takeP] - takeN;
   136	    fprintf(stderr, "Computer takes %d from pile %d\n", takeN, takeP);
   137	    return;
   138	}
   139	void hello(){
   140	    fprintf(stderr, "This is an old game of NIM.\n");
   141	    fprintf(stderr, "You should pick up at least one stone.\n");
   142	    fprintf(stderr, "And you can take at most all stones in one pile.\n");
   143	}
   144	void byebye(){
   145	    fprintf(stderr, "\nThank you for playing NIM :-)\n");
   146	}
   147	int myrandom(int lower, int upper){
   148	    static int firstFlag = 0;
   149	#ifdef TRUE_RANDOM
   150	    if(firstFlag == 0){
   151	        srand( time(0) & 0xffff );
   152	        ++firstFLAG;
   153	    }
   154	#endif
   155	    int ans = rand() % (upper-lower+1);
   156	    ans += lower;
   157	    return ans;
   158	}