-
Notifications
You must be signed in to change notification settings - Fork 1
/
maximum_product_subarray.go
74 lines (67 loc) · 1.34 KB
/
maximum_product_subarray.go
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
package leetcode
// iterative dp solution
// TC: O(n)
// SC: O(1)
func maxProduct(nums []int) int {
n := len(nums)
var res data
if nums[n-1] < 0 {
res = data{nums[n-1], 0}
} else {
res = data{0, nums[n-1]}
}
best := nums[n-1]
for i := n - 2; i >= 0; i-- {
if nums[i] == 0 {
res.negative, res.positive = 0, 0
} else if nums[i] < 0 {
res.negative, res.positive = min(nums[i], res.positive*nums[i]), res.negative*nums[i]
} else {
res.negative, res.positive = res.negative*nums[i], max(nums[i], res.positive*nums[i])
}
best = max(best, res.positive)
}
return best
}
// iterative dp solution
// TC: O(n)
// SC: O(n)
func maxProduct2(nums []int) int {
n := len(nums)
dp := make([]data, n)
if nums[n-1] < 0 {
dp[n-1] = data{nums[n-1], 0}
} else {
dp[n-1] = data{0, nums[n-1]}
}
best := nums[n-1]
for i := n - 2; i >= 0; i-- {
if nums[i] == 0 {
dp[i] = data{0, 0}
} else if nums[i] < 0 {
dp[i] = data{min(dp[i+1].positive*nums[i], nums[i]), nums[i] * dp[i+1].negative}
} else {
dp[i] = data{dp[i+1].negative * nums[i], max(nums[i]*dp[i+1].positive, nums[i])}
}
best = max(best, dp[i].positive)
}
return best
}
type data struct {
negative int
positive int
}
func max(x, y int) int {
if x > y {
return x
} else {
return y
}
}
func min(x, y int) int {
if x < y {
return x
} else {
return y
}
}