Artificial intelligence Matlab to realize the eight queen problem of backtracking

first, the purpose of the experiment:

To solve the problem of eight queens with backtracking method.

second, the experimental content:

1, read the C language writing backtracking method to solve the eight Queen problem code.

2, reference C language code, using MATLAB to write backtracking method to solve the eight Queen problem code.

3, require comments on the key code, annotated line requirements of 1/3.

Iii. List of procedures:

Queens.m

% recursive search temptation to place Queen

function q= Queens (n)

Global Indexes;

A=ones (N,n); % Initialize Checkerboard

Indexes=zeros (1,n); % record Queen's position coordinates

I=1; % line number

J=1; % column number

count=0; The number of statistical solutions in%

while (i>0)

Whilej<=n

If Judge (i,j)% will not attack the location of the other Queens

A (I,J) = 8; %8 on behalf of the Queen

Indexes (i) =j;

Break % jump out of this loop

Else

j=j+1; % probe Next Location

End

End

Ifj<=n% if you find a suitable location, find the next

i=i+1;

J=1;

Else% if no suitable location is found, backtrack, back to the previous line

I=i-1;

If i~=0

J=indexes (i);

A (I,J) = 1; % Restore Value

Indexes (i) = 0; % remove the reserved coordinates

j=j+1; % starting from the back of the last Queen

End

End

if (Indexes (n) ~=0)% If a solution is found

count=count+1;

Disp (A); % Output matrix

End

End

DISP ([Num2str (n), ' Queen problem solution number: ', NUM2STR (count)]); % output Number of solutions

End

% sub-function to determine if the position can be placed (x, y)

Judge.m

function P=judge (x, y)

Global Indexes;

% determines if the placed Queen is attacked (on the same diagonal or on the same row)

Fora=1:x-1%a as line number

B=indexes (a); %B is the column number where the Queen is placed

% if (x-y==a-b | | x+y==a+b | | x==a | | y==b)

% is judged on the same diagonal line and on the same row

if (x-y==a-b | | x+y==a+b | | y==b)% judgment is on the same diagonal and on the same column

P=0;

Return % Exit Sub-function

End

End

P=1;

End

Main function

Main.m

Clear % Data zeroing

CLC % Command Window record emptied

n=8; % Eight queens problem, set 8*8 matrix, n assigns an initial value of 8

Queens (n)% call function