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Solution_102.java
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67 lines (60 loc) · 1.35 KB
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package com.hilbert25.leetcode;
import java.util.ArrayList;
import java.util.LinkedList;
import java.util.List;
import java.util.Queue;
/**
* @author : hilbert25
* @version 创建时间：2017年5月3日 下午6:22:51 LeetCode com.hilbert25.leetcode
* Solution_102
*/
public class Solution_102 {
public static void main(String[] args) {
// TODO Auto-generated method stub
}
public class TreeNode {
int val;
TreeNode left;
TreeNode right;
TreeNode(int x) {
val = x;
}
}
public List<List<Integer>> levelOrder(TreeNode root) {
List<List<Integer>> res = new ArrayList<List<Integer>>();
if(root==null)
return res;
Queue<TreeNode> queue = new LinkedList<>();
queue.add(root);
int level = 1;
int nodeCount = 1;
while (nodeCount != 0) {
nodeCount = 0;
List<Integer> list = new ArrayList<Integer>();
for (int i = 1; i <= Math.pow(2, level - 1); i++) {
TreeNode tempNode = queue.poll();
if (tempNode != null) {
list.add(tempNode.val);
if (tempNode.left != null) {
queue.add(tempNode.left);
nodeCount++;
} else {
queue.add(null);
}
if (tempNode.right != null) {
queue.add(tempNode.right);
nodeCount++;
} else {
queue.add(null);
}
} else {
queue.add(null);
queue.add(null);
}
}
level++;
res.add(list);
}
return res;
}
}