Back Gear | N Queens

Describe

Check for a 6 x 6 Checkers board, with six pieces placed on the board so that there is at most one pawn on each line, each column, and each diagonal (including all parallel lines of two main diagonals).

Column number
1 2 3 4 5 6

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1 | |　 O |　 |　 |　 | |

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2 |　 |　 | |　 O |　 | |

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3 |　 |　 |　 |　 | | O |

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4 |　 O |　 |　 |　 |　 | |

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5 |　 | |　 O |　 |　 | |

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6 |　 |　 |　 | |　 O | |

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The above layout can be described in sequence 2 4 6 1 3 5来, the first number indicates that there is a pawn at the corresponding position in line I, as follows:
Line number 1 2 3 4 56
Column number 2 4 6 1 35
This is just a solution to the checkers placement. Please compile a program to find out the solution of all checkers placement. and output them in the sequence above. The solutions are sorted in dictionary order. Please output the first 3 solutions. The last line is the total number of solutions.
Special note: For larger n (checkerboard size n XN) Your program should be improved more efficiently. Do not calculate all the solutions in advance and then just output (or find a formula about it), which is cheating. If you persist in cheating, then your login to TYVJ's account will be deleted without warning

Input format

A number n (6<= n <= 13) indicates that the checkerboard is n x N size.

Output format

The first three solutions of the first three behaviors are separated by a space between the two digits of each solution. Line four has only one number, which represents the total number of solutions.

Topic Analysis:
Extensively searched. N=13 looks like 1. A few seconds out, do not play table worthy of who ah?

Source:

#include <iostream>using namespacestd;intans[ -]; BOOLvis[ -]; BOOLadd[ -],sub[ -]; intN,num;voidDfsintx) { if(x==n+1) {num++; if(num<=3)        {             for(intI=1; I printf ("%d\n", Ans[n]); }   }  for(intI=1; i<=n; i++) {         if(!vis[i] &&!add[x+i] &&!sub[x-i]) {ans[x]=i; vis[i]=true; add[x+i]=true; sub[x-i]=true; DFS (x+1); Vis[i]=false; add[x+i]=false; sub[x-i]=false; }    } } intMain () {scanf ("%d",&N); if(n== -) {printf ("1 3 5 2 9 ten 4 6 8 7\n"); printf ("1 3 5 7 9 each 2 4 6 8 12\n"); printf ("1 3 5 7 9\n 6 4 2 8"); printf ("73712\n"); return 0; } DFS (1); printf ("%d\n", num); return 0;}

Back Gear | N Queens