129. Sum Root to Leaf Numbers

    /** 129. Sum Root to Leaf Numbers * 2016-5-21 By Mingyang* dfs包含三种，这里是dfs的preorder方法，先解决根再是左右*/public int sumNumbers(TreeNode root) {return dfs(root, 0);}public int dfs(TreeNode root, int levelBase) {if (root == null)return 0;if (root.left == null && root.right == null) {return levelBase + root.val;}int nextLevelBase = (levelBase + root.val) * 10;int leftSubTreeSum = dfs(root.left, nextLevelBase);int rightSubTreeSum = dfs(root.right, nextLevelBase);return leftSubTreeSum + rightSubTreeSum;}//自己的代码：public int sum=0;public int sumNumbers1(TreeNode root) {dfs1(root,0);return sum;}public void dfs1(TreeNode root,int base){if(root==null)return;if(root.left==null&&root.right==null){sum+=base*10+root.val;return;}base=base*10+root.val;if(root.left!=null)dfs1(root.left,base);if(root.right!=null)dfs1(root.right,base);}