protected override int[] CheckClickPos()
{
if (ChessBoard.Instance.ChessStack.Count == 0)
{
int[] pos = new int[2];
// 随机一个位置(-2是为了避免太靠近边界，有可能使对方太过容易赢得比赛)
pos[0] = Random.Range(2, ChessBoard.Max_LINE - 2);
pos[1] = Random.Range(2, ChessBoard.Max_LINE - 2);
return(pos);
}
else
{
AILevelNode maxNode = null;
int[,] temGrid = (int[, ])ChessBoard.Instance.GetGrid();
foreach (AILevelNode child in GetChildList(temGrid, true, ChessType))
{
// 创建树 子节点为非自己，所以用false;
// 每个grid都为独立不同的方案，为了不影响独立的grid，所以Clone();
CreateTree(child, (int[, ])temGrid.Clone(), false, DeepCount);
child.score += DoAlphBeta(child, false, DeepCount, float.MinValue, float.MaxValue);
if (maxNode == null)
{
maxNode = child;
}
else
{
if (maxNode.score < child.score)
{
maxNode = child;
}
}
}
return(maxNode.pos);
}
}
// 剪枝
private float DoAlphBeta(AILevelNode node, bool isSelf, int deep, float alpha, float beta)
{
if (deep == 0 || node.score == float.MaxValue || node.score == float.MinValue)
{
return(node.score);
}
//alpha剪枝
if (isSelf)
{
foreach (AILevelNode child in node.child)
{
alpha = Mathf.Max(alpha, DoAlphBeta(child, !isSelf, deep - 1, alpha, beta));
// "="的情况下有可能出现更差的结果，所以也直接return;
if (alpha >= beta)
{
return(alpha);
}
}
return(alpha);
}
// beta剪枝
else
{
foreach (AILevelNode child in node.child)
{
beta = Mathf.Min(beta, DoAlphBeta(child, !isSelf, deep - 1, alpha, beta));
if (alpha >= beta)
{
return(beta);
}
}
return(beta);
}
}
// 创建树
private void CreateTree(AILevelNode node, int[,] grid, bool isSelf, int deep)
{
if (deep == 0 || node.score == float.MaxValue)
{
return;
}
// 设置当前点填充到地图上
grid[node.pos[0], node.pos[1]] = (int)node.chessType;
node.child = GetChildList(grid, !isSelf, node.chessType);
foreach (AILevelNode child in node.child)
{
// 创建下一级的节点,Clone()避免修改父节点的grid数据
CreateTree(child, (int[, ])grid.Clone(), !isSelf, deep - 1);
}
}
// 获取当前受益值最大或者最小Node列表
private List <AILevelNode> GetChildList(int[,] grid, bool isSelf, GameDefine.ChessType type)
{
List <AILevelNode> temList = new List <AILevelNode>();
AILevelNode node;
// 获取三个极大或极小的子节点child；
for (int i = 0; i < ChessBoard.Max_LINE; i++)
{
for (int j = 0; j < ChessBoard.Max_LINE; j++)
{
if (grid[i, j] != (int)GameDefine.DotType.NONE)
{
continue;
}
int[] pos = new int[2] {
i, j
};
node = new AILevelNode();
node.chessType = type;
node.pos = pos;
// 获取当前点的得分
if (isSelf)
{
// 最大分（当前位置的初始score = 白+黑的得分）
node.score = (GetMaxScore(grid, pos, GameDefine.ChessType.Black) + GetMaxScore(grid, pos, GameDefine.ChessType.White));
}
else
{
// 最小分 负号可取得最小值的点
node.score = (-GetMaxScore(grid, pos, GameDefine.ChessType.Black) - GetMaxScore(grid, pos, GameDefine.ChessType.White));
}
// 取出极大极小点
if (temList.Count < 4)
{
temList.Add(node);
}
else
{
foreach (AILevelNode temNode in temList)
{
if (isSelf)
{
if (temNode.score < node.score)
{
temList.Remove(temNode);
temList.Add(node);
break;
}
}
else
{
if (temNode.score > node.score)
{
temList.Remove(temNode);
temList.Add(node);
break;
}
}
}
}
}
}
return(temList);
}
