leetcode--BalancedBinaryTree

平衡二叉樹：

左右子樹深度差的絕對值不大於一，且左右子樹爲平衡二叉樹。

/**
 * Created by marsares on 15/6/12.
 */
public class BalancedBinaryTree {
    boolean isBalanced=true;
    public boolean isBalanced(TreeNode root) {
        if(root==null)return true;
        getDepth(root);
        return isBalanced;
    }
    private int getDepth(TreeNode root){
        if(root.left==null&&root.right==null)return 1;
        else if(root.left==null){
            int rightDepth=getDepth(root.right);
            if(rightDepth>1)isBalanced=false;
            return rightDepth+1;
        }
        else if(root.right==null){
            int leftDepth=getDepth(root.left);
            if(leftDepth>1)isBalanced=false;
            return leftDepth+1;
        }
        else{
            int leftDepth=getDepth(root.left);
            int rightDepth=getDepth(root.right);
            if(leftDepth-rightDepth>1||leftDepth-rightDepth<-1)isBalanced=false;
            return max(leftDepth,rightDepth)+1;
        }
    }
    private int max(int a,int b){
        return (a<b)?b:a;
    }
    public static void main(String[]args){
        TreeNode t1=new TreeNode(5);
        TreeNode t2=new TreeNode(3);
        TreeNode t3=new TreeNode(10);
        TreeNode t4=new TreeNode(2);
        TreeNode t5=new TreeNode(1);
        TreeNode t6=new TreeNode(4);
        TreeNode t7=new TreeNode(7);
        t1.left=t2;
        t1.right=t3;
        t2.left=t4;
        t2.right=t6;
        t4.left=t5;
        t3.left=t7;
        BalancedBinaryTree bbt=new BalancedBinaryTree();
        System.out.println(bbt.isBalanced(t1));
    }
}