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Original file line number Diff line number Diff line change
Expand Up @@ -99,13 +99,11 @@ class Solution:
*/
class Solution {
private int[] preorder;
private int[] inorder;
private Map<Integer, Integer> d = new HashMap<>();

public TreeNode buildTree(int[] preorder, int[] inorder) {
int n = preorder.length;
this.preorder = preorder;
this.inorder = inorder;
for (int i = 0; i < n; ++i) {
d.put(inorder[i], i);
}
Expand Down Expand Up @@ -337,43 +335,36 @@ class Solution:
```

```java
/**
* Definition for a binary tree node.
* public class TreeNode {
* int val;
* TreeNode left;
* TreeNode right;
* TreeNode() {}
* TreeNode(int val) { this.val = val; }
* TreeNode(int val, TreeNode left, TreeNode right) {
* this.val = val;
* this.left = left;
* this.right = right;
* }
* }
*/
class Solution {
private int[] preorder;
private Map<Integer, Integer> d = new HashMap<>();
private List<Integer> preorder;
private Map<Integer, List<Integer>> d = new HashMap<>();

public TreeNode buildTree(int[] preorder, int[] inorder) {
int n = preorder.length;
this.preorder = preorder;
public List<TreeNode> getBinaryTrees(List<Integer> preOrder, List<Integer> inOrder) {
int n = preOrder.size();
this.preorder = preOrder;
for (int i = 0; i < n; ++i) {
d.put(inorder[i], i);
d.computeIfAbsent(inOrder.get(i), k -> new ArrayList<>()).add(i);
}
return dfs(0, 0, n);
}

private TreeNode dfs(int i, int j, int n) {
private List<TreeNode> dfs(int i, int j, int n) {
List<TreeNode> ans = new ArrayList<>();
if (n <= 0) {
return null;
ans.add(null);
return ans;
}
int v = preorder[i];
int k = d.get(v);
TreeNode l = dfs(i + 1, j, k - j);
TreeNode r = dfs(i + 1 + k - j, k + 1, n - 1 - (k - j));
return new TreeNode(v, l, r);
int v = preorder.get(i);
for (int k : d.get(v)) {
if (k >= j && k < j + n) {
for (TreeNode l : dfs(i + 1, j, k - j)) {
for (TreeNode r : dfs(i + 1 + k - j, k + 1, n - 1 - (k - j))) {
ans.add(new TreeNode(v, l, r));
}
}
}
}
return ans;
}
}
```
Expand Down
Original file line number Diff line number Diff line change
Expand Up @@ -95,13 +95,11 @@ class Solution:
*/
class Solution {
private int[] preorder;
private int[] inorder;
private Map<Integer, Integer> d = new HashMap<>();

public TreeNode buildTree(int[] preorder, int[] inorder) {
int n = preorder.length;
this.preorder = preorder;
this.inorder = inorder;
for (int i = 0; i < n; ++i) {
d.put(inorder[i], i);
}
Expand Down
Original file line number Diff line number Diff line change
Expand Up @@ -15,13 +15,11 @@
*/
class Solution {
private int[] preorder;
private int[] inorder;
private Map<Integer, Integer> d = new HashMap<>();

public TreeNode buildTree(int[] preorder, int[] inorder) {
int n = preorder.length;
this.preorder = preorder;
this.inorder = inorder;
for (int i = 0; i < n; ++i) {
d.put(inorder[i], i);
}
Expand Down
Original file line number Diff line number Diff line change
Expand Up @@ -14,26 +14,34 @@
* }
*/
class Solution {
private int[] preorder;
private Map<Integer, Integer> d = new HashMap<>();
private List<Integer> preorder;
private Map<Integer, List<Integer>> d = new HashMap<>();

public TreeNode buildTree(int[] preorder, int[] inorder) {
int n = preorder.length;
this.preorder = preorder;
public List<TreeNode> getBinaryTrees(List<Integer> preOrder, List<Integer> inOrder) {
int n = preOrder.size();
this.preorder = preOrder;
for (int i = 0; i < n; ++i) {
d.put(inorder[i], i);
d.computeIfAbsent(inOrder.get(i), k -> new ArrayList<>()).add(i);
}
return dfs(0, 0, n);
}

private TreeNode dfs(int i, int j, int n) {
private List<TreeNode> dfs(int i, int j, int n) {
List<TreeNode> ans = new ArrayList<>();
if (n <= 0) {
return null;
ans.add(null);
return ans;
}
int v = preorder[i];
int k = d.get(v);
TreeNode l = dfs(i + 1, j, k - j);
TreeNode r = dfs(i + 1 + k - j, k + 1, n - 1 - (k - j));
return new TreeNode(v, l, r);
int v = preorder.get(i);
for (int k : d.get(v)) {
if (k >= j && k < j + n) {
for (TreeNode l : dfs(i + 1, j, k - j)) {
for (TreeNode r : dfs(i + 1 + k - j, k + 1, n - 1 - (k - j))) {
ans.add(new TreeNode(v, l, r));
}
}
}
}
return ans;
}
}
Original file line number Diff line number Diff line change
Expand Up @@ -94,11 +94,9 @@ class Solution:
*/
class Solution {
private Map<Integer, Integer> d = new HashMap<>();
private int[] inorder;
private int[] postorder;

public TreeNode buildTree(int[] inorder, int[] postorder) {
this.inorder = inorder;
this.postorder = postorder;
int n = inorder.length;
for (int i = 0; i < n; ++i) {
Expand Down
Original file line number Diff line number Diff line change
Expand Up @@ -90,11 +90,9 @@ class Solution:
*/
class Solution {
private Map<Integer, Integer> d = new HashMap<>();
private int[] inorder;
private int[] postorder;

public TreeNode buildTree(int[] inorder, int[] postorder) {
this.inorder = inorder;
this.postorder = postorder;
int n = inorder.length;
for (int i = 0; i < n; ++i) {
Expand Down
Original file line number Diff line number Diff line change
Expand Up @@ -15,11 +15,9 @@
*/
class Solution {
private Map<Integer, Integer> d = new HashMap<>();
private int[] inorder;
private int[] postorder;

public TreeNode buildTree(int[] inorder, int[] postorder) {
this.inorder = inorder;
this.postorder = postorder;
int n = inorder.length;
for (int i = 0; i < n; ++i) {
Expand Down