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phishman3579phishman3579
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Code cleanup in Interval sum and rooted tree
1 parent b6464f5 commit 75661cb

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3 files changed

+48
-36
lines changed

3 files changed

+48
-36
lines changed

‎src/com/jwetherell/algorithms/data_structures/IntervalSumArray.java‎

Lines changed: 19 additions & 14 deletions
Original file line numberDiff line numberDiff line change
@@ -1,15 +1,19 @@
11
package com.jwetherell.algorithms.data_structures;
22

3+
import java.util.List;
4+
import java.util.ArrayList;
35

46
/**
57
* Implementation of array holding integer values which allows to count sum of elements in given
68
* interval in O(log n) complexity.
7-
*
9+
* <br>
810
* @author Szymon Stankiewicz <[email protected]>
11+
* @author Justin Wetherell <[email protected]>
912
*/
1013
public class IntervalSumArray {
11-
private List.ArrayList<Integer> values = new List.ArrayList<>();
12-
private List.ArrayList<Integer> prefSums = new List.ArrayList<>();
14+
15+
private List<Integer> values = new ArrayList<Integer>();
16+
private List<Integer> prefSums = new ArrayList<Integer>();
1317

1418
/**
1519
* Creates empty IntervalSumArray
@@ -27,8 +31,7 @@ public IntervalSumArray() {
2731
* @param size size of IntervalSumArray
2832
*/
2933
public IntervalSumArray(int size) {
30-
this();
31-
for(int i = 0; i<size; i++) {
34+
for (int i = 0; i<size; i++) {
3235
values.add(0);
3336
prefSums.add(0);
3437
}
@@ -42,13 +45,12 @@ public IntervalSumArray(int size) {
4245
* @param values sequence of values for IntervalSumArray.
4346
*/
4447
public IntervalSumArray(Iterable<Integer> values) {
45-
this();
46-
for(Integer v: values)
48+
for (Integer v: values)
4749
add(v);
4850
}
4951

5052
private static int greatestPowerOfTwoDividing(int x) {
51-
return x&(-x);
53+
return x & (-x);
5254
}
5355

5456
private static int successor(int x) {
@@ -75,7 +77,7 @@ public int size() {
7577
*/
7678
public void add(int val) {
7779
values.add(val);
78-
for(int i = 1; i<greatestPowerOfTwoDividing(size()+1); i*=2)
80+
for (int i = 1; i<greatestPowerOfTwoDividing(size()+1); i*=2)
7981
val += prefSums.get(size() + 1 - i);
8082
prefSums.add(val);
8183
}
@@ -89,11 +91,12 @@ public void add(int val) {
8991
* @param val new value
9092
*/
9193
public void set(int index, int val) {
92-
if(index < 0 || index >= size()) throw new IndexOutOfBoundsException();
94+
if (index < 0 || index >= size())
95+
throw new IndexOutOfBoundsException();
9396
index++;
9497
int diff = val - values.get(index);
9598
values.set(index, val);
96-
while(index <= size()) {
99+
while (index <= size()) {
97100
int oldPrefSum = prefSums.get(index);
98101
prefSums.set(index, oldPrefSum + diff);
99102
index = successor(index);
@@ -121,10 +124,11 @@ public int get(int index) {
121124
* @return sum of values in interval
122125
*/
123126
public int sum(int end) {
124-
if(end < 0 || end >= size()) throw new IndexOutOfBoundsException();
127+
if (end < 0 || end >= size())
128+
throw new IndexOutOfBoundsException();
125129
end++;
126130
int s = 0;
127-
while(end > 0) {
131+
while (end > 0) {
128132
s += prefSums.get(end);
129133
end = predecessor(end);
130134
}
@@ -152,7 +156,8 @@ public int sum() {
152156
* @return sum of values in interval
153157
*/
154158
public int sum(int start, int end) {
155-
if(start > end) throw new IllegalArgumentException("Start must be less then end");
159+
if (start > end)
160+
throw new IllegalArgumentException("Start must be less then end");
156161
int startPrefSum = start == 0 ? 0 : sum(start-1);
157162
int endPrefSum = sum(end);
158163
return endPrefSum - startPrefSum;

‎src/com/jwetherell/algorithms/data_structures/RootedTree.java‎

Lines changed: 28 additions & 22 deletions
Original file line numberDiff line numberDiff line change
@@ -1,24 +1,32 @@
11
package com.jwetherell.algorithms.data_structures;
22

3+
import java.util.List;
34
import java.util.ArrayList;
45

56
/**
67
* Structure for storing rooted tree which allows to find lowest common ancestor.
7-
*
8+
* <p>
89
* @param <T> type of value stored in nodes.
10+
* <br>
11+
* @author Szymon Stankiewicz <[email protected]>
12+
* @author Justin Wetherell <[email protected]>
913
*/
1014
public class RootedTree<T> {
15+
16+
private final List<RootedTree<T>> ancestors = new ArrayList<RootedTree<T>>();
17+
private final List<RootedTree<T>> children = new ArrayList<RootedTree<T>>();
18+
1119
private T value = null;
1220
private int depth = 0;
13-
private final ArrayList<RootedTree<T>> ancestors = new ArrayList<>();
14-
private final ArrayList<RootedTree<T>> children = new ArrayList<>();
1521

1622
/**
1723
* Exception which can be thrown by lowestCommonAncestor function if two
1824
* nodes are in different trees.
1925
*
2026
*/
21-
public static class NodesNotInSameTreeException extends Exception {}
27+
public static class NodesNotInSameTreeException extends Exception {
28+
private static final long serialVersionUID = -5366787886097250564L;
29+
}
2230

2331
/**
2432
* Finds lower common ancestor of two nodes.
@@ -31,9 +39,11 @@ public static class NodesNotInSameTreeException extends Exception {}
3139
* @throws NodesNotInSameTreeException if nodes don't have common root
3240
*/
3341
public static <S> RootedTree<S> lowestCommonAncestor(RootedTree<S> node1, RootedTree<S> node2) throws NodesNotInSameTreeException {
34-
if(node1 == node2) return node1;
35-
else if(node1.depth < node2.depth) return lowestCommonAncestor(node2, node1);
36-
else if(node1.depth > node2.depth) {
42+
if (node1 == node2)
43+
return node1;
44+
else if (node1.depth < node2.depth)
45+
return lowestCommonAncestor(node2, node1);
46+
else if (node1.depth > node2.depth) {
3747
int diff = node1.depth - node2.depth;
3848
int jump = 0;
3949
while(diff > 0) {
@@ -43,12 +53,12 @@ else if(node1.depth > node2.depth) {
4353
diff /= 2;
4454
}
4555
return lowestCommonAncestor(node1, node2);
46-
}
47-
else {
56+
} else {
4857
try {
4958
int step = 0;
50-
while(1<<(step+1) <= node1.depth) step++;
51-
while(step >= 0) {
59+
while (1<<(step+1) <= node1.depth)
60+
step++;
61+
while (step >= 0) {
5262
if(step < node1.ancestors.size() && node1.ancestors.get(step) != node2.ancestors.get(step)) {
5363
node1 = node1.ancestors.get(step);
5464
node2 = node2.ancestors.get(step);
@@ -61,16 +71,13 @@ else if(node1.depth > node2.depth) {
6171
}
6272

6373
}
64-
6574
}
6675

6776
/**
6877
* Creates tree with root only.
6978
*
7079
*/
71-
public RootedTree() {
72-
73-
}
80+
public RootedTree() { }
7481

7582
/**
7683
* Cretes tree with root (storing value) only.
@@ -109,7 +116,7 @@ public RootedTree<T> setValue(T value) {
109116
* @return added child
110117
*/
111118
public RootedTree<T> addChild() {
112-
return new RootedTree<>(this);
119+
return new RootedTree<T>(this);
113120
}
114121

115122
/**
@@ -140,15 +147,15 @@ public T getValue() {
140147
* @return subtree with given value in the root
141148
*/
142149
public RootedTree<T> find(T value) {
143-
if(this.value == null) {
144-
if(value == null)
150+
if (this.value == null) {
151+
if (value == null)
145152
return this;
146153
}
147-
else if(this.value.equals(value))
154+
else if (this.value.equals(value))
148155
return this;
149-
for(RootedTree<T> child: children) {
156+
for (RootedTree<T> child: children) {
150157
RootedTree<T> res = child.find(value);
151-
if(res != null)
158+
if (res != null)
152159
return res;
153160
}
154161
return null;
@@ -163,5 +170,4 @@ else if(this.value.equals(value))
163170
public boolean contains(T value) {
164171
return find(value) != null;
165172
}
166-
167173
}

‎src/com/jwetherell/algorithms/data_structures/SuffixArray.java‎

Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -165,6 +165,7 @@ private String buildStringWithEndChar(CharSequence sequence) {
165165
}
166166

167167
private class KMRsWithIndex{
168+
168169
Integer beginKMR;
169170
Integer endKMR;
170171
Integer index;

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