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n_queen.c
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n_queen.c
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#include<stdio.h>
int n_queen(int board[][100],int i,int n);
void print(int board[][100],int n);
int constraints(int board[][100],int i,int j,int n);
int main(){
int i=0,n;
scanf("%d",&n);
int board[100][100]={0};
if(! n_queen(board,i,n)) printf("no sol\n");
else {
print(board,n);
printf("\n");
}
return 0;
}
int n_queen(int board[][100],int i,int n){
if(i >= n){
return 1;
}
int j;
for( j=0; j<n; j++){
board[i][j] = 1;
int good = constraints(board, i, j, n);
if(good){
int found;
found = n_queen(board,i+1,n);
if(found)
return 1;
board[i][j] = 0;
}
}
return 0;
}
int constraints(int board[][100],int i,int j,int n){
int k;
if(board[i+1][j] == 1 || board[i][j+1] == 1)
return 0;
if(board[i-1][j+1] == 1 || board[i+1][j-1] == 1)
return 0;
if(board[i+1][j+1] == 1|| board[i-1][j-1] == 1)
return 0;
if(board[i-1][j] == 1 || board[i][j-1] == 1)
return 0;
for( k = 0; k < n; k++){
if(board[i][k] == 1 )
return 0;
if(board[k][j] == 1 )
return 0;
}
return 1;
}
void print(int board[][100],int n){
int i,j;
for(i = 0; i<n; i++){
for(j=0; j<n; j++){
printf("%d ",board[i][j]);
}
printf("\n");
}
}