LeetCode110.平衡二叉树

/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
class Solution {

    public ReturnData process(TreeNode head) {
        if(head == null)
            return new ReturnData(true,0);
        
        ReturnData leftData = process(head.left);
        if(!leftData.isB)
            return new ReturnData(false,0);
        
        ReturnData rightData = process(head.right);
        if(!rightData.isB)
            return new ReturnData(false,0);
        
        if(Math.abs(leftData.h - rightData.h) > 1)
            return new ReturnData(false,0);
        return new ReturnData(true,Math.max(leftData.h,rightData.h) + 1);//因为还要算上当前结点，所以要+1
    }
    public boolean isBalanced(TreeNode root) {
        return process(root).isB;
    }
}
class ReturnData {
    boolean isB;
    int h;
    ReturnData(boolean isB,int h) {
        this.isB = isB;
        this.h = h;
    }
}