八皇后问题动态演示_Qt5实现

//核心代码如下
//Queen--放置皇后

#include "queue.h"

queue::queue()
{
    const int maxn = 9*9;
    this->QN = 4;
    this->board = new bool[maxn];
    for (int i = 0; i < maxn; i++) {
        this->board[i] = false;
    }
    this->judgeRecursion = true;
    this->count = 0;
}

queue::queue(int N)
{
    const int maxn = 81;
    if (N > 9 || N < 4)
        this->QN = 4;    //如果不合法就正规化棋盘
    else
        this->QN = N;
    this->board = new bool[maxn];
    for (int i = 0; i < maxn; ++i)  //初始化棋盘，未放置棋子的棋盘设置为false
        this->board[i] = false;
    this->judgeRecursion = true;
    this->count = 0;
}

bool queue::available (const int Crow, const int Ccol) const  //当前行，当前列
{
    for (int hor = 0; hor < Crow; ++hor) {
        //纵向查找
        if (board[hor * QN + Ccol])     //已经放置皇后的棋盘处为true
            return false;               //则返回false--放置不合法
    }
    int obli = Crow, oblj = Ccol;
    while (obli > 0 && oblj > 0) {
        if (board[(--obli) * QN + (--oblj)])
            return false;              //左斜上查找
    }
    obli = Crow, oblj = Ccol;
    while (obli > 0 && oblj < QN - 1) {
        if (board[(--obli) * QN + (++oblj)])
            return false;              //右斜上查找
    }
    return true;                       //都没有，则该位置可以放置皇后
}

//打印棋盘
void queue::show (bool *Q)
{
    const int maxn = 81;
    for (int i = 0; i < maxn; i++)
        Q[i] = this->board[i];
}

//重新初始化棋盘
void queue::reset ()
{
    const int maxn = 81;
    for (int i = 0; i < maxn; i++)
        this->board[i] = false;
    this->judgeRecursion = true;
    this->count = 0;
}

void queue::reset (int N)
{
    const int maxn = 81;
    if (N < 4 || N > 9) this->QN = 4;
    else
        this->QN = N;

    for (int i = 0; i < maxn; i++)
        this->board[i] = false;
    this->judgeRecursion = true;
    this->count = 0;
}

queue::~queue ()
{
    delete []board;
    board = nullptr;
}

/**
 * @brief queue::answer --- 放置皇后
 * @param solu --- 求解的方法数
 * @param Crow --- 当前的行数
 * @param Q --- 棋盘,用来打印
 */
void queue::answer (int solu, int cur, bool *Q)
{
    if (!judgeRecursion)   //递归结束,中断
        return;
    if (cur == QN) {                  //当前行到最后一行,则一种方案结束
        count++;
        if (count == solu) {          //递归到第solu方案时停止
            this->show (Q);
            judgeRecursion = false;   //停止递归
            return;
        }
        return;
    }
    else
    {
        for (int col = 0; col < QN; col++)
        {
            if (available (cur, col))         //检查当前行,列
            {
                board[cur * QN + col] = true; //合法则放置皇后
                answer (solu, cur + 1, Q);    //递归下一行
                //如果回溯法中使用了辅助的全局变量,则一定要及时把它们恢复原状.
                //特别的,若函数有多个出口,则需在每个出口处恢复被修改的值
                board[cur * QN + col] = false;
            }
        }
    }
}

源代码下载地址:链接：https://pan.baidu.com/s/12BTDR8pRMvxpKYNFb988EQ 密码：yk0o