标签：param integer can get money val min new 随机
The thief has found himself a new place for his thievery again. There is only one entrance to this area, called the "root." Besides the root, each house has one and only one parent house. After a tour, the smart thief realized that "all houses in this place forms a binary tree". It will automatically contact the police if two directly-linked houses were broken into on the same night.
Determine the maximum amount of money the thief can rob tonight without alerting the police.
3
/ 2 3
\ \
3 1
Maximum amount of money the thief can rob = 3 + 3 + 1 = 7.
3
/ 4 5
/ \ \
1 3 1
Maximum amount of money the thief can rob = 4 + 5 = 9.
这题一开始用递归 结果超时；随机加cache变成DP。。通过了
helper1表示抢root
helper2表示不抢root；此处注意不抢root时 即可以抢root.left和root.right 也可以不抢它们 二取其一 所以注意42-47行
1 /** 2 * Definition of TreeNode: 3 * public class TreeNode { 4 * public int val; 5 * public TreeNode left, right; 6 * public TreeNode(int x) { val = x; } 7 * } 8 */ 9 public class Solution { 10 /** 11 * @param root: The root of binary tree. 12 * @return: The maximum amount of money you can rob tonight 13 */ 14 Map<TreeNode, Integer> map1 = new HashMap<TreeNode, Integer>(); 15 Map<TreeNode, Integer> map2 = new HashMap<TreeNode, Integer>(); 16 public int houseRobber3(TreeNode root) { 17 // write your code here 18 if(root==null) return 0; 19 return Math.max(helper1(root), helper2(root)); 20 } 21 // include root 22 private int helper1(TreeNode root){ 23 if(map1.containsKey(root)){ 24 return map1.get(root); 25 } 26 int sum = root.val; 27 if(root.left!=null){ 28 sum += helper2(root.left); 29 } 30 if(root.right!=null){ 31 sum += helper2(root.right); 32 } 33 map1.put(root, sum); 34 return sum; 35 } 36 // not include root 37 private int helper2(TreeNode root){ 38 if(map2.containsKey(root)){ 39 return map2.get(root); 40 } 41 int sum = 0; 42 if(root.left!=null){ 43 sum += Math.max(helper1(root.left), helper2(root.left)); 44 } 45 if(root.right!=null){ 46 sum += Math.max(helper1(root.right), helper2(root.right)); 47 } 48 map2.put(root, sum); 49 return sum; 50 } 51 }
标签：param integer can get money val min new 随机
原文地址：http://www.cnblogs.com/xinqiwm2010/p/6835455.html
