UVA750回溯法典例-八皇后

文章代码选自UVA750-8 Queens Chess Problem的部分代码

vj题目链接:https://vjudge.net/problem/UVA-750

由于UVA中要求按照字典序输出,下面代码进行的特殊处理

代码如下:

 1 #include<cstdio>
 2 #include<algorithm>
 3 #include<cstring>
 4 using namespace std;
 5 int rnum[9];//rnum[x]:x列皇后的行编号
 6 int solution[100];
 7 int cur=1;
 8 char aim[10];
 9 
10 int pout()
11 {
12     sort(solution+1,solution+93);
13     printf("{");
14     int flag=0;
15     for(int i=1;i<93;i++)
16     {
17         if(flag)printf(",");
18         flag=1;
19         printf("%d",solution[i]);
20     }
21     printf("};");
22     //for(int i=1;i<93;i++)
23     //    printf("%d->%d\n",i,solution[i]);
24 //    printf("SOLN        COLUMN\n");
25 //    printf(" #       1 2 3 4 5 6 7 8\n\n");
26 //    for(int i=1;i<93;i++)
27 //    {
28 //        printf("%2d      ",i);
29 //        //
30 //        sprintf(aim,"%d",solution[i]);
31 //        //printf("%d->%d\n",i,solution[i]);
32 //        for(int k=0;k<8;k++)
33 //            printf(" %c",aim[k]);
34 //        printf("\n");
35 //    }
36     return 0;
37 }
38 
39 int solver(int c)
40 {
41     if(c==9)
42     {//由于该问题的结果每一组只有八个数字,为方便打表这里组合成八位的int数
43         int snum=0;
44         for(int i=1;i<9;i++)
45             snum=snum*10+(rnum[i]);
46         solution[cur++]=snum;
47         //printf("->%d\n",snum);
48     }
49     else
50     {
51         for(int r=1;r<=8;r++)
52         {
53             rnum[c]=r;
54             int ok=1;
55             for(int nc=1;nc<c;nc++)
56             {
57                 //rnum[nc]行nc列  与  rnum[c]行c列
58                 //检查每一个列,是否有与该皇后同行的存在
59                 if(rnum[nc]==rnum[c]||rnum[nc]-nc==rnum[c]-c||rnum[nc]+nc==rnum[c]+c)
60                     {ok=0;break;}
61             }//for
62             if(ok)solver(c+1);
63         }//for
64     }//else
65     return 0;
66 }
67 
68 int main()
69 {
70     memset(rnum,0,sizeof(rnum));
71     memset(solution,0,sizeof(solution));
72     memset(aim,0,sizeof(aim));
73     solver(1);
74     pout();
75     return 0;
76 }

运行上述代码,得到了结果如下:

{15863724,16837425,17468253,17582463,24683175,25713864,25741863,26174835,26831475,27368514,27581463,28613574,31758246,35281746,35286471,35714286,35841726,36258174,36271485,36275184,36418572,36428571,36814752,36815724,36824175,37285146,37286415,38471625,41582736,41586372,42586137,42736815,42736851,42751863,42857136,42861357,46152837,46827135,46831752,47185263,47382516,47526138,47531682,48136275,48157263,48531726,51468273,51842736,51863724,52468317,52473861,52617483,52814736,53168247,53172864,53847162,57138642,57142863,57248136,57263148,57263184,57413862,58413627,58417263,61528374,62713584,62714853,63175824,63184275,63185247,63571428,63581427,63724815,63728514,63741825,64158273,64285713,64713528,64718253,68241753,71386425,72418536,72631485,73168524,73825164,74258136,74286135,75316824,82417536,82531746,83162574,84136275};

将其设计为数组初始化的形式,再按照UVA题目写程序:

 1 #include<cstdio>
 2 #include<algorithm>
 3 #include<cstring>
 4 using namespace std;//下面的初始化直接将结果输入程序,减少时间
 5 int cyc[]={15863724,16837425,17468253,17582463,24683175,25713864,25741863,26174835,26831475,27368514,27581463,28613574,31758246,35281746,35286471,35714286,35841726,36258174,36271485,36275184,36418572,36428571,36814752,36815724,36824175,37285146,37286415,38471625,41582736,41586372,42586137,42736815,42736851,42751863,42857136,42861357,46152837,46827135,46831752,47185263,47382516,47526138,47531682,48136275,48157263,48531726,51468273,51842736,51863724,52468317,52473861,52617483,52814736,53168247,53172864,53847162,57138642,57142863,57248136,57263148,57263184,57413862,58413627,58417263,61528374,62713584,62714853,63175824,63184275,63185247,63571428,63581427,63724815,63728514,63741825,64158273,64285713,64713528,64718253,68241753,71386425,72418536,72631485,73168524,73825164,74258136,74286135,75316824,82417536,82531746,83162574,84136275};
 6 char aim[99][10];
 7 char psd[10];
 8 int pre()
 9 {
10     memset(psd,0,sizeof(psd));
11     for(int i=0;i<92;i++)
12     {
13         sprintf(&aim[i][1],"%d",cyc[i]);
14         aim[i][9]='\0';//重新分配成数组,方便检索
15         //printf("%s\n",&aim[i][1]);
16     }
17     return 0;
18 }
19 
20 int main()
21 {
22     int n;
23     int x,y;
24     pre();
25     scanf("%d",&n);
26     while(n--)
27     {
28         scanf("%d%d",&x,&y);
29         printf("SOLN       COLUMN\n");
30         printf(" #      1 2 3 4 5 6 7 8\n\n");
31         int kase=0;
32         char m=x+'0';
33         for(int i=0;i<92;i++)
34         {
35             if(aim[i][y]==m)
36             {
37                 printf("%2d     ",++kase);
38                 for(int k=1;k<9;k++)
39                     printf(" %c",aim[i][k]);
40                 printf("\n");
41             }
42         }
43         if(n!=0)printf("\n");//注意空行问题,最后一组的最后没有空行
44     }
45     return 0;
46 }

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转载自www.cnblogs.com/savennist/p/12201028.html
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