/*
* public class TreeNode {
* int val = 0;
* TreeNode left = null;
* TreeNode right = null;
* public TreeNode(int val) {
* this.val = val;
* }
* }
*/
public class Solution {
/**
* 代码中的类名、方法名、参数名已经指定,请勿修改,直接返回方法规定的值即可
*
*
* @param root TreeNode类
* @return int整型一维数组
*/
public int[] inorderTraversal (TreeNode root) {
// write code here
//前中后思路一致 都可以用递归实现
if(root == null){
return new int[]{};
}
//借助集合来实现
ArrayList<Integer> list = new ArrayList<>();
mid(root,list);
int[] result = new int[list.size()];
//把集合的数据放到数组
for(int i = 0;i<list.size();i++){
result[i] = list.get(i);
}
list.clear();
return result;
}
/**
* 遍历结果放到集合里面
*/
private void mid(TreeNode root,ArrayList<Integer> list){
if(root == null){
return;
}
mid(root.left,list);
list.add(root.val);
mid(root.right,list);
}
}