DFS：

public static int maxDepth_DFS(Node root) {            	if(root == null){              return 0;          }    	else{            int intLeftTreeDepth = maxDepth_DFS(root.left);              int intRightTreeDepth = maxDepth_DFS(root.right);                          return intLeftTreeDepth > intRightTreeDepth? intLeftTreeDepth + 1:intRightTreeDepth+ 1;      	}    }

BFS：

public static int maxDepth_BFS(Node root) {                if(root == null){              return 0;          }                Queue_Generic
     
       que = new Queue_Generic
      
       (1000);        int nCount = 1;        int nDepth = 0;// 记录队列里面每一层上的元素        que.Insert(root);                while(!que.isEmpty()) {            Node NodeTemp = que.PeekFront();            que.Remove();            nCount --;            //if(!NodeTemp.left.equals(null)){
                if(! (NodeTemp.left == null)){                que.Insert(NodeTemp.left);            }            //if (!NodeTemp.right.equals(null)){
                if (!(NodeTemp.right==null)){                que.Insert(NodeTemp.right);            }            if (nCount == 0) {                //System.out.println("Node Count : "+nCount);                nDepth ++;                nCount = que.Size();                //System.out.println("Node Count : "+nCount);                            }                    }        return nDepth;    }
      
     

 

其它知识

泛型队列：

public class Queue_Generic 
     
      {    int MaxSize;    T[] DataStorage;    int iHeadPos;    int iEndPos;    int iItenCount;        public Queue_Generic(int intMax){        MaxSize = intMax;        iHeadPos = 0;        iEndPos = -1;        iItenCount = 0;        DataStorage = (T[]) new Object[intMax];    }        public void Insert(T value){        if(MaxSize > iItenCount){            if(iEndPos == MaxSize-1){                iEndPos = -1;            }            DataStorage[++iEndPos] = value;            iItenCount++;        }    }        public T Remove(){        T Temp;        if(iItenCount > 0){            iItenCount--;            Temp = DataStorage[iHeadPos++];          if(iHeadPos == MaxSize){              iHeadPos = 0;          }        }        else{            return null;        }        return Temp;    }        public T Peek(){        return (T)DataStorage[iEndPos];    }        public T PeekFront(){        return (T)DataStorage[iHeadPos];    }        public boolean isEmpty(){        if(iItenCount == 0){            return true;        }else{            return false;        }    }        public boolean isFull(){        if(iItenCount == MaxSize){            return true;        }else{            return false;        }    }        public int Size(){        return iItenCount;    }}
     

其中，关键的点

1. 存储结构需要将Object强制转换成泛型类型：DataStorage = (T[]) new Object[intMax];

2. 返回的结果为泛型类型： return (T)DataStorage[iEndPos];