平衡二叉树

输入一棵二叉树，判断该二叉树是否是平衡二叉树。

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22

public class Solution {     //后续遍历时，遍历到一个节点，其左右子树已经遍历  依次自底向上判断，每个节点只需要遍历一次           private boolean isBalanced=true;     public boolean IsBalanced_Solution(TreeNode root) {                   getDepth(root);         return isBalanced;     }     public int getDepth(TreeNode root){         if(root==null)             return 0;         int left=getDepth(root.left);         int right=getDepth(root.right);                   if(Math.abs(left-right)>1){             isBalanced=false;         }         return right>left ?right+1:left+1;               } }

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23

//后续遍历二叉树，遍历过程中求子树高度，判断是否平衡 class Solution { public:     bool IsBalanced(TreeNode *root, int & dep){         if(root == NULL){             return true;         }         int left = 0;         int right = 0;         if(IsBalanced(root->left,left) && IsBalanced(root->right, right)){             int dif = left - right;             if(dif<-1 || dif >1)                 return false;             dep = (left > right ? left : right) + 1;             return true;         }         return false;     }     bool IsBalanced_Solution(TreeNode* pRoot) {         int dep = 0;         return IsBalanced(pRoot, dep);     } };