A星算法的一些关键点

A星算法的一些关键点

基本原理
C#代码

 internal abstract class AStarData
    {
        public int FSum => _gSum + _hSum;
        private int _gSum;
        private int _hSum;
        public int Direction; // 路径的方向

        /// 

        /// 计算估算的距离,有很多选择,比如曼哈顿距离, 对角线距离, 欧几里得距离, 平方后的欧几里得距离
        /// 
        /// 
        public abstract int CalcH();
    }

    class AStar where T: AStarData
    {
        private List _closeList = new List();
        private List _openList = new List();
        private T _start;
        private T _end;
        public List MainAStar()
        {
            var path = new List();
            var currentLocation = this._start;
            while (currentLocation != this._end)
            {
                currentLocation = this.ValidLocations(currentLocation)[0];
                this._openList.RemoveAt(0);
                this._closeList.Add(currentLocation);
            }
            var nextLocation = this._end;
            while (nextLocation != this._start)
            {
                nextLocation = this.CalcLocationReverse(nextLocation.Direction);
            }
            return path;
        }

        /// 

        /// 根据寻找的时候的方向,计算找到的路径
        /// 
        /// 
        /// 
        private T CalcLocationReverse(int direction)
        {
            throw new NotImplementedException();
        }

        /// 

        /// 根据当前位置,找到所有可能的位置(需要考虑封闭的路径)
        /// 需要提供要给一个方向值
        /// 需要提供已经走过的距离长度
        /// 
        /// 
        /// 
        private List CalcLocation(T start)
        {
            throw new NotImplementedException();
        }

        private List ValidLocations(T current)
        {
            var currentLocations = this.CalcLocation(current);
            this._openList.AddRange(currentLocations);
            this._openList.Sort((x, y) =>
            {
                // 从小到大排列
                if (x.FSum < y.FSum) { return -1; }
                if (x.FSum == y.FSum) { return 0; }
                return x.FSum > y.FSum ? 1 : 0;
            });
            return _openList;
        }
    }

• 路径的距离计算根据业务场景不同,自己实现
• 路径的方向也要具体定义
• 估算距离也要选择合适的实现
• 所有可到达的方格都要加入到OpenList
• 找到终点后,还要进行回溯来确定路径