20150410 Recursive implementation Eight Queens question

20150410 Recursive implementation Eight Queens question

2015-04-10 Lover Snow Child

19th century the famous mathematician Gauss 1850 presented:

Put eight queens on the 8x8 chess, so that they can not attack each other, that arbitrary even a queen can not be in the same row, the same column or a unified slash, ask how many kinds of pendulum.

Here is one of the solutions:

Mr. Gauss's calculation of the night and night, concluded that 76 kinds.

In fact the correct conclusion is 92, here we will be programmed to calculate the correct answer.

1 //Eight Queen's question2#include <stdio.h>3 4 Static intCount =0;//total number of algorithms5 6 //determine if row col position is dangerous, whether in the other Queen's attack range7 //no danger, then return True8 intNotdanger (intRowintColint(*chess) [8]){9     intI, K;Ten     intflag_1=0, flag_2=0, flag_3=0, flag_4=0, flag_5=0; One     //judging the direction of the column there is no danger sign bit flag_1 A      for(i=0; i<8; i++) -     { -         if(* (* (chess + i) + col)! =0)//determine if there are any pieces the         { -Flag_1 =1; -              Break; -         }     +     } -     //judging the upper left there is no danger sign bit flag_2 +      for(i = row, k = col; i>=0&& k>=0; I--, k--) A     { at         if(* (* (chess + i) +k)! =0) -         { -Flag_2 =1; -              Break; -         } -     } in     //judging the lower right there is no danger sign bit flag_3 -      for(i = row, k = col; i<8&& k<8; i++, k++) to     { +         if(* (* (chess + i) +k)! =0) -         { theFlag_3 =1; *              Break; $         }Panax Notoginseng     } -     //judging the upper right there is no danger sign bit flag_4 the      for(i = row, k = col; i>=0&& k<8; I--, k++) +     { A         if(* (* (chess + i) +k)! =0) the         { +Flag_4 =1; -              Break; $         } $     } -     //Judging the lower left there is no danger sign bit flag_5 -      for(i = row, k = col; i<8&& k>=0; i++, k--) the     { -         if(* (* (chess + i) +k)! =0)Wuyi         { theFlag_5 =1; -              Break; Wu         } -     } About     if(flag_1 | | flag_2 | | flag_3 | | flag_4 | |flag_5) { $         return 0; -}Else{ -         return 1; -     } A } +  the //Eight Queen algorithm row: Start Row col: number of columns *chess[8]: pointer to each row of the board - voidEightqueen (intRowintColint(*chess) [8]) $ { the     intchess_tmp[8][8], I, J; the      for(i =0; i<8; i++){ the          for(j =0; j<8; J + +){ theCHESS_TMP[I][J] =Chess[i][j]; -         } in     } the     //when the pointer has reached the eighth line, the instructions have been calculated to print out the board the     if(8==row) { Aboutprintf"method%d: \ n", count+1); the          for(i =0; i<8; i++){ the              for(j =0; j<8; J + +){ theprintf"%d", * (* (chess_tmp+i) +j)); +             } -printf"\ n"); the         }    Bayiprintf"\ n"); thecount++; the}Else{ -         //Judging if this position is dangerous, whether the other Queen's attack range -         //If there is no danger, continue to judge, know row = 8 the          for(j=0; j<col; J + +){ the             if(Notdanger (Row, J, Chess_tmp)) {//Judging whether it is dangerous the                  for(i =0; i<8; i++) {//assign a value of 0 to all columns of the entire row the* (* (chess_tmp + row) +i) =0; -                 } the* (* (chess_tmp + row) +j) =1; theEightqueen (row+1, col, chess_tmp);//Recursive invocation the             }94         } the     } the } the 98 intMainvoid) About { -     intchess[8][8], I, J;101 102     //Initialize eight Queen's chessboard, 1: Place Queen 0: no queen103      for(i =0; i<8; i++){104          for(j =0; j<8; J + +){ theCHESS[I][J] =0;106         }107     }108     109Freopen ("EightQueen.txt","W", stdout);//REDIRECT output to the OUT.txt file the 111Eightqueen (0,8, chess); theprintf"There are a total of%d solutions. \ n", count);113  the     return 0; the}

After the successful run, generate a file EightQueen.txt in the current folder, as shown in the following:

20150410 Recursive implementation Eight Queens question