void place_queen(const int col, int queen_pos[], const int max_col)
{
int i, row, conflict;
if (col == max_col) {
for (i = 0; i < max_col; ++i) {
printf("%d ", queen_pos[i]);
}
printf("\n");
return;
}
for (row = 0; row < max_col; ++row) {
conflict = 0;
for (i = 0; i < col && !conflict; ++i) {
if (queen_pos[i] == row || abs(row - queen_pos[i]) == (col - i)) {
conflict = 1;
}
}
if (!conflict) {
queen_pos[col] = row;
place_queen(col + 1, queen_pos, max_col);
}
}
}
int main(void)
{
int max_col = 8;
int queen_pos[max_col];
place_queen(0, queen_pos, max_col);
return 0;
}
void main() {
int n_solutions;
int size=14;
int board[size];
printf("size=%d\n", size);
n_solutions = place_queen(0, board, size);
printf("n_solutions=%d\n", n_solutions);
}
void place_queen(int row){
if(row == 8){
print_column(++num);
return;
}
for(int i = 0; i < 8; ++i){
column_row[row] = i;
if(check_column(row)){
place_queen(row + 1);
}
}
}
/************************************************************************
* n后问题求解
* input : n, the number of queens
* output : the vector of solution, X
************************************************************************/
int n_queens(FILE *fp,int n,int x[])
{
int nCount=0; //解个数
int k=1; //先处理第1个皇后
x[1]=0;
while(k>0)
{
x[k]=x[k]+1;//在当前列加1的位置开始搜索
while(x[k]<=n && !place_queen(x,k)) //当前列位置是否满足条件
x[k]=x[k]+1; //不满足,继续搜索下一列位置
if(x[k]<=n) //若存在满足条件的列
{
if(k==n)//是最后一个皇后，则得到一个最终解
{
//break; //此处若break,则只能得到一个解
nCount++;
output_queens(x,n); //输出
output_queens(fp,nCount,x,n);
}
else //否则，处理下一个皇后,即第 k+1 个皇后
{
k++;
x[k]=0;
}
}
else //若不存在满足条件的列,则回溯
{
x[k]=0; //第k个皇后复位为0
k--; //回溯到前一个皇后
}
}
return nCount;
}
int place_queen(int column, int board[], int size) {
int n_solutions = 0;
int is_sol;
int i, j;
// Try to place a queen in each line of <column>
for (i=0; i<size; i++) {
board[column] = i;
// Check if this board is still a solution
is_sol = true;
for (j=column-1; j>=0; j--) {
if ((board[column] == board[j]) ||
(board[column] == board[j] - (column-j)) ||
(board[column] == board[j] + (column-j))) {
is_sol = false;
break;
}
}
if (is_sol) { // It is a solution!
if (column == size-1) {
// If this is the last column, printout the solution
n_solutions += 1;
//print_solution(board, size);
} else {
// The board is not complete. Try to place the queens
// on the next level, using the current board
n_solutions += place_queen(column+1, board, size);
}
}
}
return n_solutions;
}
int main(){
place_queen(0);
return 0;
}
