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2024-12-10 15:41#ifndef _QUEENBOARD_H_
#define _QUEENBOARD_H_
const int BOARDSIZE = 8;
using namespace std;
class Queenboard {
private:
bool board[BOARDSIZE][BOARDSIZE];
public:
Queenboard();
bool is_space_under_attack(int, int) const;
void occupy_space(int, int);
void clear_column(int);
friend ostream& operator<<(ostream& out, const Queenboard& cb);
};
Queenboard::Queenboard() {
// Initialize the board to contain zero queens.
for (int row = 0; row < BOARDSIZE; row++) {
for (int col = 0; col < BOARDSIZE; col++) {
board[row][col] = false;
}
}
}
ostream& operator<<(ostream& out, const Queenboard& cb) {
// output the board
for (int row = 0; row < BOARDSIZE; row++) {
out << --------------------------------- << endl;
for (int col = 0; col < BOARDSIZE; col++) {
out << |;
if ( cb.board[row][col]) {
out << Q ;
}
else {
out << ;
}
}
out << | << endl;
}
out << --------------------------------- << endl;
return out;
}
void Queenboard::clear_column(int col) {
if (col >= BOARDSIZE || col < 0) {
throw out_of_range(Queenboard::clear_column());
}
for (int row = 0; row < BOARDSIZE; row++) {
board[row][col] = false;
}
}
void Queenboard::occupy_space(int row, int col) {
if (col >= BOARDSIZE || col < 0 ||
row >= BOARDSIZE || row < 0) {
throw out_of_range(Queenboard::occupy_space());
}
// places a queen on the board
board[row][col] = true;
}
bool Queenboard::is_space_under_attack(int row, int col) const {
if (col >= BOARDSIZE || col < 0 ||
row >= BOARDSIZE || row < 0) {
throw out_of_range(Queenboard::is_space_under_attack());
}
// check to the left
int i = col - 1;
while (i >= 0) {
if (board[row][i]) return true;
i--;
}
// check diagonal up and left
int j = row - 1;
int k = col - 1;
while (j >= 0 && k >= 0) {
if (board[j][k]) return true;
j--; k--;
}
// check diagonal down and left
j = row + 1;
k = col - 1;
while (j < BOARDSIZE && k >= 0) {
if (board[j][k]) return true;
j++; k--;
}
return false;
}
#endif
#include <iostream>
#include <cstdlib>
#include <stdexcept>
#include Queenboard.h
using namespace std;
bool place_queens(Queenboard& qb, int col);
int main(int argc, char* argv[]) {
try {
Queenboard qb;
if (! place_queens(qb, 0)) {
cout << No solution found.\n;
}
return EXIT_SUCCESS;
}
catch (exception& e) {
cerr << e.what() << \n;
}
catch (...) {
cerr << Unknown exception caught.\n;
}
return EXIT_FAILURE;
}
bool place_queens(Queenboard& qb, int col) {
bool inserted = false;
for (int row = 0; row < BOARDSIZE; row++) {
if (! qb.is_space_under_attack(row, col)) {
// insert a queen
qb.occupy_space(row, col);
inserted = true;
if (col == BOARDSIZE - 1) {
// solution found!
cout << qb << \n;
return true;
}
else {
// place a queen in the next column
if (place_queens(qb, col + 1)) {
return true;
}
else {
inserted = false;
}
}
}
}
if (! inserted) {
// backtrack to previous column
qb.clear_column(col - 1);
return false;
}
}
课本上应该有吧
找本C++的书看看行了
没想法了
这样算是最佳解
class Queen8{
static final int QueenMax = 8;
static int oktimes = 0;
static int chess[] = new int[QueenMax];
public static void main(String args[]){
for (int i=0;i<QueenMax;i++)chess[i]=-1;
placequeen(0);
System.out.println(\n\n\n八皇后共有+oktimes+个解法 made by yifi 2003);
}
public static void placequeen(int num)
{
int i=0;
boolean qsave[] = new boolean[QueenMax];
for(;i<QueenMax;i++) qsave[i]=true;
i=0;
while (i<num){
qsave[chess[i]]=false;
int k=num-i;
if ( (chess[i]+k >= 0) && (chess[i]+k < QueenMax) ) qsave[chess[i]+k]=false;
if ( (chess[i]-k >= 0) && (chess[i]-k < QueenMax) ) qsave[chess[i]-k]=false;
i++;
}
for(i=0;i<QueenMax;i++){
if (qsave[i]==false)continue;
if (num<QueenMax-1){
chess[num]=i;
placequeen(num+1);
}
else{ //num is last one
chess[num]=i;
oktimes++;
System.out.println(这是第+oktimes+个解法 如下:);
System.out.println(第n行: 1 2 3 4 5 6 7 8);
for (i=0;i<QueenMax;i++){
String row=第+(i+1)+行: ;
if (chess[i]==0);
else
for(int j=0;j<chess[i];j++) row+=--;
row+=++;
int j = chess[i];
while(j<QueenMax-1){row+=--;j++;}
System.out.println(row);
}
}
}
}
}