【LeetCode-337】House Robber III

看到了别人的好的方法，记录一下，注释什么的都在代码里

//dfs解决public class HouseRobberIII {public class TreeNode {int val;TreeNode left;TreeNode right;TreeNode(int x) {val = x;}}public int rob(TreeNode root) {if(root == null){return 0;}int[] res = robHelp(root);return Math.max(res[0], res[1]);    }/** * dfs all the nodes of the tree, each node return two number, int[] num,  * num[0] is the max value while rob this node,  * num[1] is max value while not rob this value.  * Current node return value only depend on its children's value.  * Transform function should be very easy to understand. * @param root * @return */public int[] robHelp(TreeNode root){if(root == null){return new int[2];}int[] left = robHelp(root.left);int[] right = robHelp(root.right);int[] res = new int[2];res[0] = left[1] + right[1] + root.val;//这里的两个max还是比较精髓的，想清楚为什么这样(left[0] 不一定比left[1]大)res[1] = Math.max(left[0], left[1]) + Math.max(right[0], right[1]);return res;}}