C-language Learning-eight queens question

Problem Description:

Put eight queens on the 8x8 chess, so that they can not attack each other, that is, any two queens can not be in the same row, the same column or the same slash, ask how many kinds of pendulum.

Programming:

1, one-dimensional array a[17], the array is divided into three paragraphs, the first paragraph a[0] used to mark the completion of the eight Queen placement; the second paragraph a[1,8] is used to mark the column position with or without children, convenient to judge the column conflict; The third paragraph a[9,16] is used to mark the storage location.

2, the key algorithm recursive judgment position, Eightqueens.

3, diagonal position mutually exclusive judgment, isdiagonal.

4, Output function, Printresult.

Algorithm Description:

1, first passed into the array A and the starting column variable I=1, to determine whether the marked A[0] is 1, 1 into 2, otherwise enter 3;

2, print array a[9,16];

3, test whether J is less than 8, under the end of recursion, or the detection of J-column is legal, legally enter 4, otherwise j + +, re-walk 3;

4, column labeled A[j] 1, storage location tag A[8+i] I,J combination of Location Code (I*10+J);

5. Judge if all queens have been placed, then mark as a[0] 1.

6, column number plus 1, recursion again.

7, clear the value of this recursive setting, in order to facilitate backtracking, re-look for other combinations, return 3.

1 /*2 function: Eight Queens3 time: 2014-08-31 14:34:564 */5#include <stdio.h>6 7 intc =1;//Simple Paging8 9 voidEightqueens (int*a,inti);//Recursive SolutionTen intIsdiagonal (int*a,intn);//Judging whether the same diagonal One voidPrintresult (int*A);//Output Results A  - intMainvoid) - { the     inta[ -]; -     inti; -      -     //Initialize the board +      for(i=0; i< -; i++) -     { +A[i] =0; A     } at  -     //Solution Method -Eightqueens (A,1); -      -     return 0; - } in  - voidEightqueens (int*a,inti) to { +     intJ; -  the     if(a[0]==1) *     { $         //Output ResultsPanax Notoginseng Printresult (a); -     } the     Else +     { A          for(j=1; j<9; J + +) the         { +             if(A[j]! =1&& isdiagonal (A, i*Ten+J))//non-peers, non-identical columns, no longer diagonal lines.  -             { $A[J] =1; $a[8+i] = i*Ten+J; -                 if(i = =8) a[0] =1; -                 //Recursive the                 if(i<=8) -                 {WuyiEightqueens (A, i+1); the                 } -A[J] =0; Wua[8+i] =0; -a[0] =0; About             } $         } -     } -      - } A  + //Judging whether the same diagonal the intIsdiagonal (int*a,intN) - { $     intADCD, abit;//tagged row and column coordinates the     intNDCD, NBit;//the coordinates of the rows to be judged the     intTDCD, Tbit;//marked and pending row difference values the     intK; the  -NDCD = n/Ten; inNBit = n%Ten; the  the      for(k=9; k< -; k++) About     { the         if(A[k]! =0) the         { the             //separating rows and columns of tagged coordinates +ADCD = a[k]/Ten; -Abit = a[k]%Ten; the             BayiTDCD = NDCD-ADCD;//Calculate the row difference value theTbit = Nbit-abit;//Calculate column Difference values the  -             if((tdcd-tbit) = =0|| (TDCD + tbit) = =0)//The absolute values of the row and column differences are equal in the same diagonal -             { the                 return 0; the             } the         } the         Else -         { the             return 1; the         } the     }94     return 1; the } the  the //Output Results98 voidPrintresult (int*a) About { -     intm;101 102printf"Scheme%d: \ n", c);103      for(m=9; m< -; m++)104     { theprintf"a[%d]\t", A[m]);106     }107printf"\ n");108     109C++; the 111     if(c%Ten==0){ the GetChar ();113     } the}

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C-language Learning-eight queens question