八皇后---递归

 

#include<iostream>
#include<vector>
#include<string.h>
#include<unistd.h>
#include<stdlib.h>
#include<stdio.h>
using namespace std;

int occupy[8][8] = {0}; //8*8棋盘上记录占据的位置
int mylocation[8] = {0};//记录当前正在计算的每行的索引
vector< vector<int> > locations; //记录所以8皇后的解

//8*8棋盘每个位置初始化
void fillOccupy(int occupyBegin[8][8], int value=9)
{
    for(int i = 0; i < 8; i++)
    {
        for(int j = 0; j < 8; j++)
        {
            occupyBegin[i][j]=value;
        }
    }
}

//打印8*8棋盘的当前布局
void showCur(int occupyBegin[8][8])
{
    for(int i = 0; i < 8; i++)
    {
        for(int j = 0; j < 8; j++)
        {
            cout<<occupyBegin[i][j]<<"  ";
        }
        cout<<endl;
    }
    cout<<endl;
}

//选定8*8棋盘的一个位置后，将这个位置所影响后续行的位置都进行占据标志设置(取决于用户传value是非0)
//选定8*8棋盘的一个位置后，将这个位置所影响后续行的位置都清除占据标志设置(取决于用户传value是0)
void setOccupy(int occupyBegin[8][8], int curRow, int curColum, int value, int lengthRow, int lengthColumn)
{
    //设置后续行的斜右行
    for(int iRow = curRow; iRow < lengthRow; ++iRow)
    {
        if(curColum+iRow-curRow >= lengthColumn)
        {
            break;
        }
        occupyBegin[iRow][curColum+(iRow-curRow)] = value;
    }

    //设置后续行的斜左行
    for(int iRow = curRow; iRow < lengthRow; ++iRow)
    {
        if(curColum-iRow+curRow < 0)
        {
            break;
        }
        occupyBegin[iRow][curColum-(iRow-curRow)] = value;
    }

    //设置后续行的竖行
    for(int iRow = curRow; iRow < lengthRow; ++iRow)
    {
        occupyBegin[iRow][curColum] = value;
    }

    if(value != 0)
    {
        occupyBegin[curRow][curColum]=1;
    }
}


//测试占据函数
void testSetOccupy()
{
    cout<<endl<<"------00------"<<endl;
    setOccupy(occupy, 0,0,1,8,8);
    showCur(occupy);
    setOccupy(occupy, 0,0,0,8,8);

    cout<<endl<<"------01------"<<endl;
    setOccupy(occupy, 0,1,1,8,8);
    showCur(occupy);
    setOccupy(occupy, 0,1,0,8,8);

    cout<<endl<<"------23------"<<endl;
    setOccupy(occupy, 2,3,1,8,8);
    showCur(occupy);
    setOccupy(occupy, 2,3,0,8,8);

    cout<<endl<<"-----27-------"<<endl;
    setOccupy(occupy, 2,7,1,8,8);
    showCur(occupy);
    setOccupy(occupy, 2,7,0,8,8);

    cout<<endl<<"------77------"<<endl;
    setOccupy(occupy, 7,7,1,8,8);
    showCur(occupy);
    setOccupy(occupy, 7,7,0,8,8);

    cout<<endl<<"------clear43-----"<<endl;
    fillOccupy(occupy);
    showCur(occupy);
    cout<<endl<<"*******************"<<endl;
    setOccupy(occupy, 4,3,0,8,8);
    showCur(occupy);
    fillOccupy(occupy,0);
}


void Calcu(int occupyBegin[8][8], int location[8], int curRow, int lengthRow, int lengthColumn)
{
    //遍历此行的每一个列
    for(int i = 0; i < lengthColumn; i++)
    {
        //找到列中可用的位置，同时把此位置影响的后面行的格子占据住
        if (occupy[curRow][i] == 0)
        {
            location[curRow] = i;  //location里面记录此行占据的位置
            setOccupy(occupyBegin, curRow, i, 9, lengthRow, lengthColumn); //占据影响的后面的格子

            if(curRow == lengthRow -1) /*如果有位置占用并且现在行是最后一行，那么vector记录次序,继续在最后一行找下一个位置。 */
            {
                vector<int> value;
                for(int k = 0; k < lengthColumn; ++k)
                {
                    value.push_back(location[k]);
                }

                locations.push_back(value);


                int tmp[8][8]={0};
                cout<<"find a sequence: ";
                for(int k = 0; k < lengthColumn; ++k)
                {
                    cout<<location[k]<< "   ";
                    setOccupy(tmp,k,location[k],9,lengthRow, lengthColumn);
                }
                cout<<endl;
                showCur(tmp);
            }
            else //不是最后一行的话让下一行开始找
            {
                //递归让下一行继续找位置
                Calcu(occupyBegin, location,curRow+1, lengthRow, lengthColumn);
            }

            //当前行把当前占据位置影响的格子情况清除掉，然后当前行找下一个可用位置
            /*整个占据情况清掉后，把当前行的之前行再重新设置一遍占用*/
            fillOccupy(occupyBegin, 0);
            for(int j = 0; j < curRow; j++)
            {
                setOccupy(occupyBegin, j, location[j],9,lengthRow, lengthColumn);
            }
        }
    }
}


int main(int argc, char** argv)
{
    Calcu(occupy, mylocation, 0, 8, 8);
    cout<< locations.size()<<endl;
//testSetOccupy();
};