N皇后

//main.c
// 1.cpp : Defines the entry point for the console application.
//
#include "stdio.h"
#include "queen.h"

int main(int argc, char* argv[])
{
    printf("\nnum = %d\n",queen(12));
    return 0;
}

dbg.h

#ifndef        _MRCHEN_DBG_H_
#define        _MRCHEN_DBG_H_
    //#define    MY_DEBUG
    void    dbgprint(char *sz_msg);
#endif

dbg.c

#include    "stdio.h"
#include    "dbg.h"

void    dbgprint(char *sz_msg)
{
    #ifdef    MY_DEBUG
        printf("FILE : %s  LINE : %d\n\tMSG : %s\n",__FILE__,__LINE__,sz_msg);
    #endif
}

queen.h

#ifndef    _MRCHEN_2_H_
#define    _MRCHEN_2_H_
#ifndef    BOOL
#define    BOOL    char    
#define    FALSE    0      
#define    TRUE    1      
#endif

typedef    struct    _tagPanel{
    char        *panel_p;//排列
    int         count;//找到的排列的种数
    int         x,y;//
    int         n;//棋盘的size
}PANEL,*PPANEL;

//查看(x_i,y_i)位置是否合法
static    BOOL    init_panel(int    n);

static    void    clean_panel();

static    BOOL    check();

static    BOOL    set(int    i);

static    BOOL    next();

static    int    next_line();
static    int    prev_line();

BOOL      print();

int    queen(int    n);
        
#endif

queen.c

#include    "malloc.h"
#include    "string.h"
#include    "queen.h"
#include    "dbg.h"
#define        MY_DEBUG

static    PANEL        pan_st;

int    queen(int    n)
{    
    int    i = 0;
    int    ln;
    //init    
    if(FALSE == init_panel(n)){
        dbgprint("init failed");
        return    -1;
    }
    //loop
    for(i = 0;i < (n>>1);i++){
        set(i);
        next_line();
        do{
            if(!check()){
                if(next()){
                    continue;    
                }
                if(prev_line()==0){
                    break;
                }
                continue;
            }else{
                if(pan_st.n != next_line()){
                    continue;
                }else{
                //    print();
                    pan_st.count++;
                    if(next()){
                        continue;
                    }
                    if(prev_line()==0){
                        break;
                    }
                }
            }

        }while(1);
    }
    //clean
    clean_panel();
    return    pan_st.count<<=1;
}


//init panel ,ok
static    BOOL    init_panel(int    n)
{
    dbgprint("init_panel");
    pan_st.panel_p = (char*)malloc(n*sizeof(char));
    if(pan_st.panel_p == NULL){
        return    FALSE;
    }
    pan_st.count = 0;
    pan_st.n = n;
    pan_st.x = pan_st.y = 0;
    return    TRUE;
}

//destroy panel,ok
static    void    clean_panel()
{
    dbgprint("clean_panel");
    if(pan_st.panel_p != NULL){
        free(pan_st.panel_p);
    }
}


//check
static    BOOL    check()
{
    int    i = 0;

    dbgprint("check");
    for(i=0;i < pan_st.y ;i++){
        if(pan_st.panel_p[i] == pan_st.x){
        //    printf("i = %d  (y,x) = (%d,%d)  pan_st.panel_p[%d] = %d\n",
        //            i,pan_st.y,pan_st.x,i,pan_st.panel_p[i]);
            return    FALSE;
        }
        if((pan_st.y-i) == (pan_st.x-pan_st.panel_p[i])
            ||(pan_st.y-i)==-(pan_st.x-pan_st.panel_p[i])){
            
        //        printf("i = %d  (y,x) = (%d,%d)  pan_st.panel_p[%d] = %d\n",
        //                i,pan_st.y,pan_st.x,i,pan_st.panel_p[i]);
                    
            return    FALSE;
        }
    }
    //printf("%d---%d\n",pan_st.y,pan_st.x);
    return    TRUE;
}


//set first
static    BOOL    set(int    x)
{
    dbgprint("set");
    if(x >= pan_st.n || x<0){
        return    FALSE;
    }
    pan_st.x = x;
    pan_st.y = 0;
    pan_st.panel_p[0] = x;
    return    TRUE;
}


//get next
static    BOOL    next()
{
    dbgprint("next");
    do{
        if(pan_st.x+1 == pan_st.n){
            return    FALSE;
        }
        pan_st.panel_p[pan_st.y] = ++pan_st.x;
    }while(!check());
    return    TRUE;
}


//return    next line
static    int    next_line()
{
    int    i = pan_st.y+1;
    dbgprint("next_line");
    if(i < pan_st.n ){
        //printf("\n\ty = %d  x = %d\n",pan_st.y,pan_st.x);
        pan_st.panel_p[pan_st.y] = pan_st.x;        
        pan_st.y++;
        pan_st.x = 0;
    }
    return    i;
}

//return    previous line
static    int    prev_line()
{
    int    i = 0;
    dbgprint("prev_line");
    while(0!=(i=--pan_st.y)){
        pan_st.panel_p[pan_st.y] += 1;
        if(pan_st.panel_p[pan_st.y] < pan_st.n){
            pan_st.x = pan_st.panel_p[pan_st.y];
            break;
        }else{
            continue;
        }
    }
    return    i;
}


//print the panel,ok
BOOL      print()
{
    int    i = 0,j = 0;
    dbgprint("print");
    for(; i < pan_st.n ;i++){
        for(j=0;j < pan_st.n; j++){
            if(pan_st.panel_p[i] != j){
                printf("O ");
            }else{
                printf("# ");
            }
        }
        printf("\n");
    }
    puts("=========================");
    return    TRUE;
}

makefile

cc	=	cc
obj	=	main.o\
		queen.o\
		dbg.o
targets	:	$(obj)
	$(cc)	$(obj)	-o	main
main.o	:	main.c
queue.o	:	queen.h
dbg.o	:	dbg.h
clean:
	rm	*.o
	rm	main