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Commit ce10dd9

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Renamed Tree to RootedTree and added 'contains' and 'find' methods to RootedTree
1 parent 6163af3 commit ce10dd9

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3 files changed

+92
-53
lines changed

3 files changed

+92
-53
lines changed

‎src/com/jwetherell/algorithms/data_structures/Tree.java‎ renamed to ‎src/com/jwetherell/algorithms/data_structures/RootedTree.java‎

Lines changed: 42 additions & 10 deletions
Original file line numberDiff line numberDiff line change
@@ -7,10 +7,11 @@
77
*
88
* @param <T> type of value stored in nodes.
99
*/
10-
public class Tree<T> {
10+
public class RootedTree<T> {
1111
private T value = null;
1212
private int depth = 0;
13-
private final ArrayList<Tree<T>> ancestors = new ArrayList<>();
13+
private final ArrayList<RootedTree<T>> ancestors = new ArrayList<>();
14+
private final ArrayList<RootedTree<T>> children = new ArrayList<>();
1415

1516
/**
1617
* Exception which can be thrown by lowestCommonAncestor function if two
@@ -29,7 +30,7 @@ public static class NodesNotInSameTreeException extends Exception {}
2930
* @return lower common ancestor
3031
* @throws NodesNotInSameTreeException if nodes don't have common root
3132
*/
32-
public static <S> Tree<S> lowestCommonAncestor(Tree<S> node1, Tree<S> node2) throws NodesNotInSameTreeException {
33+
public static <S> RootedTree<S> lowestCommonAncestor(RootedTree<S> node1, RootedTree<S> node2) throws NodesNotInSameTreeException {
3334
if(node1 == node2) return node1;
3435
else if(node1.depth < node2.depth) return lowestCommonAncestor(node2, node1);
3536
else if(node1.depth > node2.depth) {
@@ -67,7 +68,7 @@ else if(node1.depth > node2.depth) {
6768
* Creates tree with root only.
6869
*
6970
*/
70-
public Tree() {
71+
public RootedTree() {
7172

7273
}
7374

@@ -76,11 +77,12 @@ public Tree() {
7677
*
7778
* @param value value to be stored in root
7879
*/
79-
public Tree(T value) {
80+
public RootedTree(T value) {
8081
this.value = value;
8182
}
8283

83-
private Tree(Tree<T> parent) {
84+
private RootedTree(RootedTree<T> parent) {
85+
parent.children.add(this);
8486
this.ancestors.add(parent);
8587
this.depth = parent.depth + 1;
8688
int dist = 0;
@@ -94,7 +96,7 @@ private Tree(Tree<T> parent) {
9496
}
9597
}
9698

97-
public Tree<T> setValue(T value) {
99+
public RootedTree<T> setValue(T value) {
98100
this.value = value;
99101
return this;
100102
}
@@ -106,8 +108,8 @@ public Tree<T> setValue(T value) {
106108
*
107109
* @return added child
108110
*/
109-
public Tree<T> addChild() {
110-
return new Tree<>(this);
111+
public RootedTree<T> addChild() {
112+
return new RootedTree<>(this);
111113
}
112114

113115
/**
@@ -118,7 +120,7 @@ public Tree<T> addChild() {
118120
* @param value value to be stored in new child
119121
* @return added child
120122
*/
121-
public Tree<T> addChild(T value) {
123+
public RootedTree<T> addChild(T value) {
122124
return addChild().setValue(value);
123125
}
124126

@@ -131,5 +133,35 @@ public T getValue() {
131133
return value;
132134
}
133135

136+
/**
137+
* Finds subtree with given value in the root.
138+
*
139+
* @param value value to be find
140+
* @return subtree with given value in the root
141+
*/
142+
public RootedTree<T> find(T value) {
143+
if(this.value == null) {
144+
if(value == null)
145+
return this;
146+
}
147+
else if(this.value.equals(value))
148+
return this;
149+
for(RootedTree<T> child: children) {
150+
RootedTree<T> res = child.find(value);
151+
if(res != null)
152+
return res;
153+
}
154+
return null;
155+
}
156+
157+
/**
158+
* Returns true if tree contains a node with given value
159+
*
160+
* @param value to be checked
161+
* @return true if tree contains node with given value, false otherwise
162+
*/
163+
public boolean contains(T value) {
164+
return find(value) != null;
165+
}
134166

135167
}
Lines changed: 50 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,50 @@
1+
package com.jwetherell.algorithms.data_structures;
2+
3+
import org.junit.Test;
4+
5+
import static org.junit.Assert.*;
6+
7+
public class RootedTreeTest {
8+
9+
@Test
10+
public void largeTreeTest() throws RootedTree.NodesNotInSameTreeException {
11+
RootedTree<Integer> root = new RootedTree<>();
12+
RootedTree<Integer> left = root.addChild();
13+
RootedTree<Integer> middle = root.addChild();
14+
RootedTree<Integer> right = root.addChild();
15+
16+
//long path
17+
RootedTree<Integer> v = left;
18+
for(int i = 0; i<1000; i++)
19+
v = v.addChild();
20+
RootedTree<Integer> leftRight = left.addChild();
21+
22+
assertEquals(RootedTree.lowestCommonAncestor(v, leftRight), left);
23+
24+
for(int i = 0; i<2000; i++) {
25+
leftRight = leftRight.addChild();
26+
27+
assertEquals(RootedTree.lowestCommonAncestor(v, leftRight), left);
28+
}
29+
30+
assertEquals(RootedTree.lowestCommonAncestor(middle, right), root);
31+
assertEquals(RootedTree.lowestCommonAncestor(root, right), root);
32+
assertEquals(RootedTree.lowestCommonAncestor(root, root), root);
33+
34+
RootedTree<Integer> root2 = new RootedTree<>();
35+
boolean thrownException = false;
36+
try {
37+
RootedTree.lowestCommonAncestor(v, root2);
38+
} catch (RootedTree.NodesNotInSameTreeException e) {
39+
thrownException = true;
40+
}
41+
assertTrue(thrownException);
42+
43+
RootedTree<Integer> deepChild = v.addChild(101);
44+
assertEquals(deepChild, root.find(101));
45+
assertTrue(root.contains(101));
46+
47+
assertNull(root.find(102));
48+
assertFalse(root.contains(102));
49+
}
50+
}

‎test/com/jwetherell/algorithms/data_structures/TreeTest.java‎

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