-
Notifications
You must be signed in to change notification settings - Fork 0
/
algo.go
153 lines (131 loc) · 3.4 KB
/
algo.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
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
package intervals
import (
"sort"
"github.com/relvox/iridescence_go/maths"
)
func FindCover[T Number](intervals [][2]T) []T {
switch {
case len(intervals) <= 10_000:
return FindCover2(intervals)
case len(intervals) <= 100_000:
return FindCover3(intervals)
default:
return FindCover1(intervals)
}
}
func FindCover1[T Number](intervals [][2]T) []T {
if len(intervals) == 0 {
return []T{}
}
// Sort intervals by their starting point
sort.Slice(intervals, func(i, j int) bool {
return intervals[i][0] < intervals[j][0]
})
var result []T
start, end := intervals[0][0], intervals[0][1]
for _, interval := range intervals {
if interval[0]-1 <= end {
// Overlapping intervals, move the end if needed
if interval[1] > end {
end = interval[1]
}
} else {
// Non-overlapping interval, add the previous interval and reset start and end
result = append(result, start, end)
start, end = interval[0], interval[1]
}
}
// Add the last interval
result = append(result, start, end)
return result
}
func FindCover2[T Number](intervals [][2]T) []T {
if len(intervals) == 0 || len(intervals) >= 20_000 {
return nil
}
if len(intervals) == 1 {
return intervals[0][:]
}
// Custom insertion sort for potentially better performance in nearly-sorted data
for i := 1; i < len(intervals); i++ {
j := i
for j > 0 && intervals[j][0] < intervals[j-1][0] {
intervals[j], intervals[j-1] = intervals[j-1], intervals[j]
j--
}
}
// In-place merge intervals
idx := 0
for _, interval := range intervals {
if maths.MinValue[T]() == interval[0] || interval[0]-1 <= intervals[idx][1] {
if interval[1] > intervals[idx][1] {
intervals[idx][1] = interval[1]
}
} else {
idx++
intervals[idx] = interval
}
}
// Flatten the intervals into a single slice
result := make([]T, 0, 2*(idx+1))
for i := 0; i <= idx; i++ {
result = append(result, intervals[i][0], intervals[i][1])
}
return result
}
func FindCover3[T Number](intervals [][2]T) []T {
if len(intervals) == 0 {
return nil
}
if len(intervals) == 1 {
return intervals[0][:]
}
// Sort intervals by their starting point
sort.SliceStable(intervals, func(i, j int) bool {
return intervals[i][0] < intervals[j][0]
})
// In-place merge intervals
idx := 0
for _, interval := range intervals {
if maths.MinValue[T]() == interval[0] || interval[0]-1 <= intervals[idx][1] {
if interval[1] > intervals[idx][1] {
intervals[idx][1] = interval[1]
}
} else {
idx++
intervals[idx] = interval
}
}
// Flatten the intervals into a single slice
result := make([]T, 0, 2*(idx+1))
for i := 0; i <= idx; i++ {
result = append(result, intervals[i][0], intervals[i][1])
}
return result
}
func FindCover4[T Number](intervals [][2]T) []T {
if len(intervals) == 0 {
return []T{}
}
// Sort intervals by their starting point
sort.SliceStable(intervals, func(i, j int) bool {
return intervals[i][0] < intervals[j][0]
})
var result []T
start, end := intervals[0][0], intervals[0][1]
for _, interval := range intervals {
if interval[0]-1 <= end {
// Overlapping intervals, move the end if needed
if interval[1] > end {
end = interval[1]
}
} else {
// Non-overlapping interval, add the previous interval and reset start and end
result = append(result, start, end)
start, end = interval[0], interval[1]
}
}
// Add the last interval
result = append(result, start, end)
return result
}