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Commit 6b360fe

Browse files
Add C++ implementation
Signed-off-by: begeekmyfriend <begeekmyfriend@gmail.com>
1 parent b8bb232 commit 6b360fe

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5 files changed

+91
-31
lines changed

5 files changed

+91
-31
lines changed

‎0105_construct_binary_tree_from_preorder_and_inorder_traversal/binary_tree_build.c‎

Lines changed: 1 addition & 10 deletions
Original file line numberDiff line numberDiff line change
@@ -73,15 +73,6 @@ static int find(int num, int size, struct hlist_head *heads)
7373
return -1;
7474
}
7575

76-
static struct TreeNode *node_new(int val)
77-
{
78-
struct TreeNode *tn = malloc(sizeof(*tn));
79-
tn->val = val;
80-
tn->left = NULL;
81-
tn->right = NULL;
82-
return tn;
83-
}
84-
8576
static struct TreeNode *dfs(int *preorder, int pre_low, int pre_high, int *inorder,
8677
int in_low, int in_high, struct hlist_head *in_heads, int size)
8778
{
@@ -107,7 +98,7 @@ static void node_add(int val, int index, int size, struct hlist_head *heads)
10798

10899
static struct TreeNode *buildTree(int *preorder, int preorderSize, int *inorder, int inorderSize)
109100
{
110-
int i, j;
101+
int i;
111102
struct hlist_head *in_heads = malloc(inorderSize * sizeof(*in_heads));
112103
for (i = 0; i < inorderSize; i++) {
113104
INIT_HLIST_HEAD(&in_heads[i]);
Lines changed: 39 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,39 @@
1+
#include <bits/stdc++.h>
2+
3+
using namespace std;
4+
5+
/**
6+
* Definition for a binary tree node.
7+
* struct TreeNode {
8+
* int val;
9+
* TreeNode *left;
10+
* TreeNode *right;
11+
* TreeNode() : val(0), left(nullptr), right(nullptr) {}
12+
* TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
13+
* TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
14+
* };
15+
*/
16+
class Solution {
17+
public:
18+
TreeNode* buildTree(vector<int>& preorder, vector<int>& inorder) {
19+
for (int i = 0; i < inorder.size(); i++) {
20+
map_[inorder[i]] = i;
21+
}
22+
int size = inorder.size();
23+
return dfs(preorder, 0, size - 1, inorder, 0, size - 1);
24+
}
25+
26+
private:
27+
unordered_map<int, int> map_;
28+
TreeNode* dfs(vector<int>& preorder, int pre_lo, int pre_hi, vector<int>& inorder, int in_lo, int in_hi) {
29+
if (pre_lo > pre_hi || in_lo > in_hi) {
30+
return nullptr;
31+
}
32+
int value = preorder[pre_lo];
33+
TreeNode *root = new TreeNode(value);
34+
int index = map_[value];
35+
root->left = dfs(preorder, pre_lo + 1, pre_lo + (index - in_lo), inorder, in_lo, index - 1);
36+
root->right = dfs(preorder, pre_hi - (in_hi - index) + 1, pre_hi, inorder, index + 1, in_hi);
37+
return root;
38+
}
39+
};

‎0106_construct_binary_tree_from_inorder_and_postorder_traversal/binary_tree_build.c‎

Lines changed: 8 additions & 17 deletions
Original file line numberDiff line numberDiff line change
@@ -73,15 +73,6 @@ static int find(int num, int size, struct hlist_head *heads)
7373
return -1;
7474
}
7575

76-
static struct TreeNode *node_new(int val)
77-
{
78-
struct TreeNode *tn = malloc(sizeof(*tn));
79-
tn->val = val;
80-
tn->left = NULL;
81-
tn->right = NULL;
82-
return tn;
83-
}
84-
8576
static void node_add(int val, int index, int size, struct hlist_head *heads)
8677
{
8778
struct order_node *on = malloc(sizeof(*on));
@@ -91,23 +82,23 @@ static void node_add(int val, int index, int size, struct hlist_head *heads)
9182
hlist_add_head(&on->node, &heads[hash]);
9283
}
9384

94-
static struct TreeNode *dfs(int *inorder, int in_low, int in_high, int *postorder,
95-
int post_low, int post_high, struct hlist_head *in_heads, int size)
85+
static struct TreeNode *dfs(int *inorder, int in_lo, int in_hi, int *postorder,
86+
int post_lo, int post_hi, struct hlist_head *in_heads, int size)
9687
{
97-
if (in_low > in_high || post_low > post_high) {
88+
if (in_lo > in_hi || post_lo > post_hi) {
9889
return NULL;
9990
}
10091
struct TreeNode *tn = malloc(sizeof(*tn));
101-
tn->val = postorder[post_high];
102-
int index = find(postorder[post_high], size, in_heads);
103-
tn->left = dfs(inorder, in_low, index - 1, postorder, post_low, post_low + (index - 1 - in_low), in_heads, size);
104-
tn->right = dfs(inorder, index + 1, in_high, postorder, post_high - (in_high - index), post_high - 1, in_heads, size);
92+
tn->val = postorder[post_hi];
93+
int index = find(postorder[post_hi], size, in_heads);
94+
tn->left = dfs(inorder, in_lo, index - 1, postorder, post_lo, post_lo + (index - 1 - in_lo), in_heads, size);
95+
tn->right = dfs(inorder, index + 1, in_hi, postorder, post_hi - (in_hi - index), post_hi - 1, in_heads, size);
10596
return tn;
10697
}
10798

10899
static struct TreeNode *buildTree(int *inorder, int inorderSize, int *postorder, int postorderSize)
109100
{
110-
int i, j;
101+
int i;
111102
struct hlist_head *in_heads = malloc(inorderSize * sizeof(*in_heads));
112103
for (i = 0; i < inorderSize; i++) {
113104
INIT_HLIST_HEAD(&in_heads[i]);
Lines changed: 39 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,39 @@
1+
#include <bits/stdc++.h>
2+
3+
using namespace std;
4+
5+
/**
6+
* Definition for a binary tree node.
7+
* struct TreeNode {
8+
* int val;
9+
* TreeNode *left;
10+
* TreeNode *right;
11+
* TreeNode() : val(0), left(nullptr), right(nullptr) {}
12+
* TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
13+
* TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
14+
* };
15+
*/
16+
class Solution {
17+
public:
18+
TreeNode* buildTree(vector<int>& inorder, vector<int>& postorder) {
19+
for (int i = 0; i < inorder.size(); i++) {
20+
map_[inorder[i]] = i;
21+
}
22+
int size = inorder.size();
23+
return dfs(inorder, 0, size - 1, postorder, 0, size - 1);
24+
}
25+
26+
private:
27+
unordered_map<int, int> map_;
28+
TreeNode* dfs(vector<int>& inorder, int in_lo, int in_hi, vector<int>& postorder, int post_lo, int post_hi) {
29+
if (in_lo > in_hi || post_lo > post_hi) {
30+
return nullptr;
31+
}
32+
int value = postorder[post_hi];
33+
TreeNode *root = new TreeNode(value);
34+
int index = map_[value];
35+
root->left = dfs(inorder, in_lo, index - 1, postorder, post_lo, post_lo + (index - in_lo - 1));
36+
root->right = dfs(inorder, index + 1, in_hi, postorder, post_hi - (in_hi - index), post_hi - 1);
37+
return root;
38+
}
39+
};

‎0124_binary_tree_maximum_path_sum/bst_max_path.c‎

Lines changed: 4 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -20,18 +20,18 @@ static int dfs(struct TreeNode *root, int *max)
2020
}
2121

2222
/* In case of negative node value */
23-
int l = maximum(dfs(root->left, max), 0);
24-
int r = maximum(dfs(root->right, max), 0);
23+
int subl = maximum(dfs(root->left, max), 0);
24+
int subr = maximum(dfs(root->right, max), 0);
2525

26-
int sum = root->val + l + r;
26+
int sum = root->val + subl + subr;
2727
if (sum > *max) {
2828
*max = sum;
2929
}
3030

3131
/* The return value does not equal the sum value
3232
* since we need to return path through the root node
3333
*/
34-
return root->val + maximum(l, r);
34+
return root->val + maximum(subl, subr);
3535
}
3636

3737
static int maxPathSum(struct TreeNode* root)

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