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
|
/**
* Copyright © 2014 Mattias Andrée (maandree@member.fsf.org)
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
package algorithms.searching;
import java.util.*;
import java.math.*;
/**
* Hybrid interpolation search class. Interpolation search runs in logarithmic
* time, in average, and linear time in worst case, which will occur with
* rough distrubitions, constant memory, and requires the list to be sorted
* and numerical. Interpolation search often out preforms binary search for
* smoothing distributions. Hybrid interpolation search uses interpolation
* search and falls back to linear search when the number of elemetns left are
* small enough. Identity search is not possible, only equality search.<br>
* The list must be sorted in ascending order.
*/
public class HybridInterpolationSearch
{
£>for T in char byte short int long float double; do
/**
* Find the easiest to find occurance of an item in a list
*
* @param item The item to find
* @param array The list in which to search
* @param fallback The number of elements at when to fall back to linear search
* @return The index of the easiest to find occurance of the item. The bitwise
* negation of the position it insert it in is returned if it was not found.
*/
public static int indexOf(£{T} item, £{T}[] array, int fallback)
{
£{T} low, high, at;
int min = 0, mid;
int max = array.length - 1;
for (;;)
{
if (min + fallback >= max)
return linearFirst(item, array, min, max);
if ((low = array[min]) > item) break;
if ((high = array[max]) < item) break;
if ((at = array[mid = min + (int)((item - low) * (max - min) / (high - low))]) < item)
min = mid + 1;
else if (at > item)
max = mid - 1;
else
return mid;
}
return (array[min] == item) ? min : ~min;
}
£>done
£>for T in BigInteger BigDecimal; do
/**
* Find the easiest to find occurance of an item in a list
*
* @param item The item to find
* @param array The list in which to search
* @param fallback The number of elements at when to fall back to linear search
* @return The index of the easiest to find occurance of the item. The bitwise
* negation of the position it insert it in is returned if it was not found.
*/
public static int indexOf(£{T} item, £{T}[] array, int fallback)
{
£{T} low, high, at;
int min = 0, mid;
int max = array.length - 1;
for (;;)
{
if (min + fallback >= max)
return linearFirst(item, array, min, max);
if ((low = array[min]).compareTo(item) > 0) break;
if ((high = array[max]).compareTo(item) < 0) break;
mid = item.subtract(low).multiply(£{T}.valueOf(max - min)).divide(high.subtract(low)).intValue();
if ((at = array[mid += min]).compareTo(item) < 0)
min = mid + 1;
else if (at.compareTo(item) > 0)
max = mid - 1;
else
return mid;
}
return (array[min] == item) ? min : ~min;
}
£>done
£>for T in char byte short int long float double Object; do . src/comparable
/**
* Finds the index of the first occurance of an item in a list
*
* @param item The item for which to search
* @param array The list in which to search
* @param start Offset for the list or search range
* @param end End of the list or search range
* @return The index of the first occurance of the item within the list, {@code -1} if it was not found
*/
private static int linearFirst(£{T} item, £{T}[] array, int start, int end)
{
/* This is nearly identical to LinearSearch.indexOfFirst */
int i = start < 0 ? (array.length - start) : start;
int n = end < 0 ? (array.length - end) : end;
for (;;)
{
if (i == n)
break;
if (£(equal "array[i]" item))
return i;
i++;
}
return -1;
}
£>done
}
|
