【LeetCode】199. Binary Tree Right Side View
阿新 • • 發佈:2019-01-28
Problem:Given a binary tree, imagine yourself standing on the right side of it, return the values of the nodes you can see ordered from top to bottom.
題目:給定一個二叉樹,輸出從右側看到的節點(大致就是每層的最右側的節點).
思路:做的二叉樹的深度遍歷
1.節點是否為空,不為空則記錄節點。
2.遞迴查詢根節點的左孩子,是否為空,不為空記錄在該層節點陣列中
3.遞迴查詢根節點的右孩子,是否為空,不為空記錄在該層節點陣列中
/** * Definition for a binary tree node. * public class TreeNode { * int val; * TreeNode left; * TreeNode right; * TreeNode(int x) { val = x; } * } */ class Solution { public List<Integer> rightSideView(TreeNode root) { List<Integer> ret = new ArrayList<Integer>(); if (root == null) { return ret; } int height = getHeight(root, 0); TreeNode[] edgeMap = new TreeNode[height]; setRightEdge(root, 0, edgeMap); for (int i = 0; i < height; i++) { ret.add(edgeMap[i].val); } return ret; } // refined for this problem public void setRightEdge(TreeNode node, int l, TreeNode[] rightEdge) { if (node == null) { return; } rightEdge[l]=node; setRightEdge(node.left, l+1,rightEdge); setRightEdge(node.right, l+1,rightEdge); } // get the height of treenode public int getHeight(TreeNode node, int l) { if (node == null) { return l; } return Math.max(getHeight(node.left, l + 1), getHeight(node.right, l + 1)); } }