[1,2,4,5,3],[4,2,5,1,3]

[1,3,5]

import java.util.*;
public class Solution {
//建树函数
//四个int参数分别是前序最左节点下标，前序最右节点下标
//中序最左节点下标，中序最右节点坐标
public TreeNode buildTree(int[] xianxu, int l1, int r1, int[] zhongxu, int l2, int r2){
if(l1 > r1 || l2 > r2)
return null;
//构建节点
TreeNode root = new TreeNode(xianxu[l1]);
//用来保存根节点在中序遍历列表的下标
int rootIndex = 0;
//寻找根节点
for(int i = l2; i <= r2; i++){
if(zhongxu[i] == xianxu[l1]){
rootIndex = i;
break;
}
}
//左子树大小
int leftsize = rootIndex - l2;
//右子树大小
int rightsize = r2 - rootIndex;
//递归构建左子树和右子树
root.left = buildTree(xianxu, l1 + 1, l1 + leftsize, zhongxu, l2 , l2 + leftsize - 1);
root.right = buildTree(xianxu, r1 - rightsize + 1, r1, zhongxu, rootIndex + 1, r2);
return root;
}

//深度优先搜索函数
public ArrayList<Integer> rightSideView(TreeNode root) {
//右边最深处的值
Map<Integer, Integer> mp = new HashMap<Integer, Integer>();
//记录最大深度
int max_depth = -1;
//维护深度访问节点
Stack<TreeNode> nodes = new Stack<TreeNode>();
//维护dfs时的深度
Stack<Integer> depths = new Stack<Integer>();
nodes.push(root);
depths.push(0);
while(!nodes.isEmpty()){
TreeNode node = nodes.pop();
int depth = depths.pop();
if(node != null){
//维护二叉树的最大深度
max_depth = Math.max(max_depth, depth);
//如果不存在对应深度的节点我们才插入
if(mp.get(depth) == null)
mp.put(depth, node.val);
nodes.push(node.left);
nodes.push(node.right);
depths.push(depth + 1);
depths.push(depth + 1);
}
}
ArrayList<Integer> res = new ArrayList<Integer>();
//结果加入链表
for(int i = 0; i <= max_depth; i++)
res.add(mp.get(i));
return res;
}

public int[] solve (int[] xianxu, int[] zhongxu) {
//空节点
if(xianxu.length == 0)
return new int[0];
//建树
TreeNode root = buildTree(xianxu, 0, xianxu.length - 1, zhongxu, 0, zhongxu.length - 1);
//获取右视图输出
ArrayList<Integer> temp = rightSideView(root);
//转化为数组
int[] res = new int[temp.size()];
for(int i = 0; i < temp.size(); i++)
res[i] = temp.get(i);
return res;
}
}