#题目描述：
给出一个二叉树如下图所示：
6/ \7 9\ / -2 6
请由该二叉树生成一个新的二叉树，它满足其树中的每个节点将包含原始树中的左子树和右子树的和。
20(7-2+9+6)/ \-2 6\ / 0 0
左子树表示该节点左侧叶子节点为根节点的一颗新树；右子树表示该节点右侧叶子节点为根节点的一颗新树
输入描述：
2行整数，第1行表示二叉树的中序遍历，第2行表示二叉树的前序遍历，以空格分割
例如：
7 -2 6 6 9
6 7 -2 9 6
输出描述：
1行整数，表示求和树的中序遍历，以空格分割
例如：
输出
-2 0 20 0 6
示例1
输入：
-3 12 6 8 9 -10 -7
8 12 -3 6 -10 9 -7
输出：
0 3 0 7 0 2 0
题解
恶心人的题目，同一个知识点，重复写几遍
源码 Java
public class CalTree {static Input input;static {input = new Input("-3 12 6 8 9 -10 -7\n" +"8 12 -3 6 -10 9 -7");input = new Input("7 -2 6 6 9\n" +"6 7 -2 9 6");}static StringBuffer result = new StringBuffer();public static void main(String[] args) {String[] s1 = input.nextLine().split(" ");String[] s2 = input.nextLine().split(" ");int[] mid = new int[s1.length];for (int i = 0; i < s1.length; i++) {mid[i] = Integer.parseInt(s1[i]);}int[] pre = new int[s2.length];for (int i = 0; i < s2.length; i++) {pre[i] = Integer.parseInt(s2[i]);}TreeNode root = rebuild(mid, pre);merge(root);dfs(root);System.out.println(result.toString().trim());}public static void dfs(TreeNode root) {if (root == null) {return;}dfs(root.left);result.append(root.val + " ");dfs(root.right);}public static int merge(TreeNode root) {if (root == null) {return 0;}int left = merge(root.left);int right = merge(root.right);int ret = root.val + left + right;root.val = left + right;return ret;}public static TreeNode rebuild(int[] mid, int[] pre) {if (mid.length == 1){return new TreeNode(mid[0]);}if (mid.length == 0){return null;}TreeNode root = new TreeNode(pre[0]);int index = -1;for (int i = 0; i < mid.length; i++) {if (root.val == mid[i]){index = i;break;}}int[] leftMid = new int[index];int[] leftPre = new int[index];for (int i = 0; i < index; i++) {leftMid[i] = mid[i];leftPre[i] = pre[i+1];}root.left = rebuild(leftMid, leftPre);int len = mid.length - leftMid.length - 1;int[] rightMid = new int[len];int[] rightPre = new int[len];for (int i = index + 1, j = 0; i < mid.length; i++, j++) {rightMid[j] = mid[i];rightPre[j] = pre[i];}root.right = rebuild(rightMid, rightPre);return root;}static class TreeNode{public int val;public TreeNode left;public TreeNode right;public TreeNode(int val) {this.val = val;}}
}
