原帖及讨论：http://bbs.bccn.net/thread-112551-1-1.html

#include <iostream>
using namespace std;
typedef char chess[10];
typedef int temparr[10];
chess arr;
temparr brr;
int number,suc,c3,n2,c2,n1,c1;
char ch;
void inarrdata(chess a)
{
    a[1]='1';a[2]='2';a[3]='3';
    a[4]='4';a[5]='5';a[6]='6';
    a[7]='7';a[8]='8';a[9]='9';
}
void display(chess a)
{
    cout<<endl;cout<<endl;
    cout<<"  "<<a[1]<<" "<<'|'<<" "<<a[2]<<" "<<'|'<<" "<<a[3]<<endl;
    cout<<" -----------"<<endl;
    cout<<"  "<<a[4]<<" "<<'|'<<" "<<a[5]<<" "<<'|'<<" "<<a[6]<<endl;
    cout<<" -----------"<<endl;
    cout<<"  "<<a[7]<<" "<<'|'<<" "<<a[8]<<" "<<'|'<<" "<<a[9]<<endl;
    cout<<endl;cout<<endl;
}
int arrfull()
{
    int i;
    int arrf=0;
    for(i=1;i<=9;i++)
        if(i==arr[i]-48)
            arrf=1;
    return arrf;
}
void cn(int line)
{
    switch(line)
        {
            case 0:c3=c3+1;break;
            case 1:n2=n2+1;break;
            case 2:c2=c2+1;break;
            case 3:n1=n1+1;break;
            case 4:c1=c1+1;break;
        }
}
int linenum(char a,char b,char c)
{
    int ln=5;
    if((a=='X')&&(b=='X')&&(c=='X'))
        ln=0;
    if(((a=='O')&&(b=='O')&&(c!='O'))||((a=='O')&&(b!='O')&&(c=='O'))||((a!='O')&&(b=='O')&&(c=='O')))
        ln=1;
    if(((a=='X')&&(b=='X')&&(c!='X'))||((a=='X')&&(b!='X')&&(c=='X'))||((a!='X')&&(b=='X')&&(c=='X')))
        ln=2;
    if(((a=='O')&&(b!='O')&&(c!='O'))||((a!='O')&&(b=='O')&&(c!='O'))||((a!='O')&&(b!='O')&&(c=='O')))
        ln=3;
    if(((a=='X')&&(b!='X')&&(c!='x'))||((a!='X')&&(b=='X')&&(c!='X'))||((a!='X')&&(b!='X')&&(c=='X')))
        ln=4;
    return ln;
}
int maxbrr(int *br)
{
    int temp,i,mb;
    temp=-888;
    for(i=1;i<=9;i++)
        {
            if(temp<=br[i])
                {
                    temp=br[i];
                    mb=i;
                }
        }
    return mb;
}
void manstep() //人走棋处理模块
{
    int j;
    display(arr);
    if(arrfull())  //如果棋盘上还有下棋的位置，给人走一步棋
        {
            cout<<"您要走哪一步？请输入数字（1--9）:";
            cin>>j;
            while((j<1)||(j>9)||(j!=arr[j]-48))
                {
                    cout<<"对不起，您输入的数字不对，请重新输入（1--9）:";
                    cin>>j;
                }
            arr[j]='O';
        }
}
void computerstep()  //计算机走棋处理模块
{
    int i;
    if(arrfull())  //如果棋盘上还有可下棋的位置，则计算机走棋
        {
            for(i=1;i<=9;i++)  //对每一步可走的棋进行计算
                {
                    if(i==arr[i]-48)
                        {
                            c3=0;n2=0;c2=0;n1=0;c1=0;
                            arr[i]='X';
                            number=linenum(arr[1],arr[2],arr[3]);cn(number);
                            number=linenum(arr[4],arr[5],arr[6]);cn(number);
                            number=linenum(arr[7],arr[8],arr[9]);cn(number);
                            number=linenum(arr[1],arr[4],arr[7]);cn(number);
                            number=linenum(arr[2],arr[5],arr[8]);cn(number);
                            number=linenum(arr[3],arr[6],arr[9]);cn(number);
                            number=linenum(arr[1],arr[5],arr[9]);cn(number);
                            number=linenum(arr[3],arr[5],arr[7]);cn(number);
                            brr[i]=(128*c3-63*n2+31*c2-15*n1+7*c1);   //计算此步权值
                            arr[i]=i+48;
                        }
                    else
                        brr[i]=-999;
                }
            arr[maxbrr(brr)]='X';    //确定计算机走哪一步，权值最大的一步
            c3=0;n2=0;c2=0;n1=0;c1=0;
             number=linenum(arr[1],arr[2],arr[3]);cn(number);
             number=linenum(arr[4],arr[5],arr[6]);cn(number);
             number=linenum(arr[7],arr[8],arr[9]);cn(number);
             number=linenum(arr[1],arr[4],arr[7]);cn(number);
             number=linenum(arr[2],arr[5],arr[8]);cn(number);
             number=linenum(arr[3],arr[6],arr[9]);cn(number);
             number=linenum(arr[1],arr[5],arr[9]);cn(number);
             number=linenum(arr[3],arr[5],arr[7]);cn(number);
             if(c3!=0)                //计算机已赢
                {
                    display(arr);
                    cout<<endl;
                    cout<<"计算机赢了!!!"<<endl;
                    exit(0);
                    suc=0;
                }
        }
    else
        suc=0;
}
int main()
{
    cout<<"游戏规则："<<endl<<"棋盘格式如图，人和计算机在棋盘上交替走棋"<<endl;
    cout<<"约定计算机使用符号X，人使用符号O"<<endl;
    cout<<"谁先使一横行或一竖行或对角线上有三个自己的符号，就胜利了！"<<endl;
    inarrdata(arr);          //棋盘坐标编号
    display(arr);            //显示初始棋盘
    suc=1;
    cout<<"请选择您是否先走?(y/n)";
    cin>>ch;
    if((ch=='y')||(ch=='Y'))    //输入Y，表示人先走棋
        {
            while(suc)
                {
                    manstep();
                    computerstep();
                }
            display(arr);
        }
    else                           //计算机先走棋
        {
            while(suc)
                {
                    computerstep();
                    if(suc)
                        manstep();
                }
        }
    cout<<endl<<"和棋!"<<endl;
    return 0;
}