博弈算法实现三子棋
用博弈树算法实现井字棋游戏。 井字棋游戏是一种简单的棋类游戏，在3*3的棋盘上，两人轮流下子，谁的棋子先连成3颗一条直线，谁就赢了，可以横着、竖着、斜着。博弈树算法是用搜索来解决这类问题的算法，井字棋游戏步数较少，很容易用博弈树算法实现
#include//如果下一步棋盘的评价值小于本层节点的极值，则置本层极值为更小者，即后辈结点极小值<=祖先节点极大值
flag = temp;
if (flag <= val) //如果本层的极值已经小于上一层的评价值，则不需要搜索下去，剪枝 A剪枝
out = true;
}
else //如果上一层为极小层，算法与上面刚好相反
{
cur[i][j] = 1;//该位置填上电脑玩家棋子
if (CheckWin() == 1)//如果电脑玩家赢了，置棋盘评价值为正无穷
temp = 10000;
else
temp = cut(flag, dep + 1, !max); // 否则继续调用ab剪枝函数
if (temp>flag) //如果下一步棋盘的评价值大于本层节点的极值，则置本层极值为更小者，即后辈结点极大值>=祖先节点极小值
flag = temp;
if (flag >= val) //如果本层的极值已经大于上一层的评价值，则不需要搜索下去，剪枝 B剪枝
out = true;
}
cur[i][j] = 0; //把模拟下的一步棋还原，回溯
}
}
}
if (max) //根据上一层是否为极大层，用本层的极值修改上一层的评价值
{
if (flag>val)
val = flag;
}
else
{
if (flagreturn flag; //函数返回的是本层的极值
}
//用户通过此函数来输入落子的位置，
//比如，用户输入31，则表示用户在第3行第1列落子。
void UserInput()
{
int pos, x, y;
L1: cout << "Please input your qizi (xy):\n ";
cin >> pos;
x = pos / 10, y = pos % 10;
if (x>0 && x<4 && y>0 && y<4 && cur[x - 1][y - 1] == 0)
{
cur[x - 1][y - 1] = -1;
}
else
{
cout << "Input Error!\n";
goto L1;
}
}
//主程序
int main()
{
int m = -10000, val = -10000, dep = 1; //m 用来存放最大的val
int x_pos, y_pos; //记录最佳走步的坐标
Init();
cout << "Qipan: " << endl;
PrintQP();
char IsFirst;
cout << "Do you want do first?(y/n)";
cin >> IsFirst;
while (IsFirst != 'y'&&IsFirst != 'n')
{
cout << "ERROR!" << "Do you want do first?(y/n)";
cin >> IsFirst;
}
if (IsFirst == 'y')
{
L4: // 人先走
UserInput();
PrintQP();
cout << endl;
num++;
value();
if (q == 0)
{
cout << "DOWN GAME!" << endl;
system("pause");
return 0;
}
if (CheckWin() == -1)
{
cout << "You Win! GAME OVER." << endl;
system("pause");
return 0;
}
for (int x = 0; x<3; x++)
for (int y = 0; y<3; y++){
if (cur[x][y] == 0){
cur[x][y] = 1;
cut(val, dep, 1);
if (CheckWin() == 1) {
cout << "The computer put the qizi at:" << x + 1 << y + 1 << endl;
PrintQP();
cout << "The computer WIN! GAME OVER." << endl;
system("pause");
return 0;
}
if (val>m) {
m = val;
x_pos = x; y_pos = y;
}
val = -10000;
cur[x][y] = 0;
}
}
cur[x_pos][y_pos] = 1;
val = -10000; m = -10000; dep = 1;
cout << "The computer put the qizi at:" << x_pos + 1 << y_pos + 1 << endl;
PrintQP();
cout << endl;
num++;
value();
if (q == 0)
{
cout << "DOWN GAME!" << endl;
system("pause");
return 0;
}
goto L4;
}
else
{ // 计算机先走
L5:
for (int x = 0; x<3; x++)
for (int y = 0; y<3; y++){
if (cur[x][y] == 0){
cur[x][y] = 1;
cut(val, dep, 1);
if (CheckWin() == 1) {
cout << "The computer put the qizi at:" << x + 1 << y + 1 << endl;
PrintQP();
cout << "The computer WIN! GAME OVER." << endl;
system("pause");
return 0;
}
if (val>m) {
m = val;
x_pos = x; y_pos = y;
}
val = -10000;
cur[x][y] = 0;
}
}
cur[x_pos][y_pos] = 1;
val = -10000; m = -10000; dep = 1;
cout << "The computer put the qizi at:" << x_pos + 1 << y_pos + 1 << endl;
PrintQP();
cout << endl;
num++;
value();
if (p == 0)
{
cout << "DOWN GAME!" << endl;
system("pause");
return 0;
}
UserInput();
PrintQP();
cout << endl;
num++;
value();
if (p == 0)
{
cout << "DOWN GAME!" << endl;
system("pause");
return 0;
}
if (CheckWin() == -1)
{
cout << "Conguatulations! You Win! GAME OVER." << endl;
system("pause");
return 0;
}
goto L5;
}
system("pause");
return 0;
}
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