-
Notifications
You must be signed in to change notification settings - Fork 0
/
merge_sorted_array.php
91 lines (77 loc) · 2.31 KB
/
merge_sorted_array.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
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
<?php
$nums1 = [1, 2, 3, 0, 0, 0];
$nums2 = [2, 5, 6];
$m = 3;
$n = 3;
/**
* Merge Sorted Array
* @link https://leetcode.com/problems/merge-sorted-array
*
* Note: $nums1 array contain zeros that should be ignored,
* zeros added for not being worried about memory that array take - $nums1 has exact length of result (merged arrays)
*/
/**
* Approach:
* Initialize two pointers for two arrays,
* start iterating from the end of arrays,
* iterate until both pointers are less than 0,
* check which array value is higher and push value to result array starting from the end.
*
* Time complexity - O(n)
* Space complexity - O(1)
*/
function merge(&$nums1, $m, $nums2, $n)
{
if ($m === 0) {$nums1 = $nums2; return;}
if ($n === 0) {return;}
$firstPointer = $m - 1;
$secondPointer = $n - 1;
$countdown = count($nums1) - 1;
while ($firstPointer >= 0 || $secondPointer >= 0) {
$firstItem = $nums1[$firstPointer] ?? null;
$secondItem = $nums2[$secondPointer] ?? null;
if ($secondItem === null || $firstItem !== null && $firstItem > $secondItem) {
$nums1[$countdown--] = $firstItem;
$firstPointer--;
} else {
$nums1[$countdown--] = $secondItem;
$secondPointer--;
}
}
}
/**
*
* Approach:
* Initialize two pointers for two arrays,
* start iterating from the beginning of arrays,
* iterate through until both pointers are equal to length of arrays,
* check which array value is less and push this value to result array starting from the beginning
* copy result to $nums1.
*
* Time complexity - O(n)
* Space complexity - O(n)
*/
function mergeAnotherApproach(&$nums1, $m, $nums2, $n)
{
if ($m === 0) {
$nums1 = $nums2;
return;
} elseif ($n === 0) {
return;
}
$firstPointer = 0;
$secondPointer = 0;
$result = [];
while ($firstPointer < $m || $secondPointer < $n) {
$firstItem = $firstPointer < $m ? $nums1[$firstPointer] : false;
$secondItem = $nums2[$secondPointer] ?? false;
if ($secondItem === false || $firstItem !== false && $firstItem < $secondItem) {
$result[] = $firstItem;
$firstPointer++;
} else {
$result[] = $secondItem;
$secondPointer++;
}
}
$nums1 = $result;
}