-
Notifications
You must be signed in to change notification settings - Fork 17
/
path_in_tree.php
74 lines (64 loc) · 1.83 KB
/
path_in_tree.php
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
<?php
/**
* 剑指 Offer 系列:二叉树中和为某一值的路径
* Author:学院君
*/
require "./binary_tree_node.php";
/**
* 实现函数
* @param BinaryTreeNode $root
* @param int $expectedSum
*/
function FindPathInTree(BinaryTreeNode $root, int $expectedSum): void
{
if ($root == null) {
return;
}
$path = new SplStack();
$currentSum = 0;
FindPath($root, $expectedSum, $path, $currentSum);
}
/**
* 核心实现代码
* @param BinaryTreeNode $node
* @param int $expectedSum
* @param SplStack $stack
* @param int $currentSum
*/
function FindPath(BinaryTreeNode $node, int $expectedSum, SplStack $path, int $currentSum): void
{
$currentSum += $node->data;
$path->push($node->data);
// 如果是叶子结点,判断路径上结点的和是否等于输入的值
// 如果相等,则打印这条路径
$isLeaf = $node->left == null && $node->right == null;
if ($isLeaf && $currentSum == $expectedSum) {
printf("满足条件的路径找到了: ");
$path->rewind();
while ($path->valid()) {
printf("%d\t", $path->current());
$path->next();
}
printf("\n");
}
// 如果不是叶子结点,则继续遍历其子结点
if ($node->left) {
FindPath($node->left, $expectedSum, $path, $currentSum);
}
if ($node->right) {
FindPath($node->right, $expectedSum, $path, $currentSum);
}
// 返回父节点前,在路径上删除当前结点
$path->pop();
}
$root = new BinaryTreeNode();
$root->data = 10;
$root->left = new BinaryTreeNode();
$root->left->data = 5;
$root->right = new BinaryTreeNode();
$root->right->data = 12;
$root->left->left = new BinaryTreeNode();
$root->left->left->data = 4;
$root->left->right = new BinaryTreeNode();
$root->left->right->data = 7;
FindPathInTree($root, 22);