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Merge branch 'master' of https://github.com/eugenp/tutorials

This commit is contained in:
Eugen 2019-07-28 09:34:32 +03:00
parent b8d65f954b 1ab13b226d
commit 6350819aa6
4 changed files with 178 additions and 0 deletions
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72
data-structures/src/main/java/com/baeldung/graph/Graph.java Normal file
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@ -0,0 +1,72 @@
package com.baeldung.graph;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Stack;
public class Graph {
private Map<Integer, List<Integer>> adjVertices;
public Graph() {
this.adjVertices = new HashMap<Integer, List<Integer>>();
}
public void addVertex(int vertex) {
adjVertices.putIfAbsent(vertex, new ArrayList<>());
}
public void addEdge(int src, int dest) {
adjVertices.get(src).add(dest);
}
public void dfsWithoutRecursion(int start) {
Stack<Integer> stack = new Stack<Integer>();
boolean[] isVisited = new boolean[adjVertices.size()];
stack.push(start);
while (!stack.isEmpty()) {
int current = stack.pop();
isVisited[current] = true;
System.out.print(" " + current);
for (int dest : adjVertices.get(current)) {
if (!isVisited[dest])
stack.push(dest);
}
}
}
public void dfs(int start) {
boolean[] isVisited = new boolean[adjVertices.size()];
dfsRecursive(start, isVisited);
}
private void dfsRecursive(int current, boolean[] isVisited) {
isVisited[current] = true;
System.out.print(" " + current);
for (int dest : adjVertices.get(current)) {
if (!isVisited[dest])
dfsRecursive(dest, isVisited);
}
}
public void topologicalSort(int start) {
Stack<Integer> result = new Stack<Integer>();
boolean[] isVisited = new boolean[adjVertices.size()];
topologicalSortRecursive(start, isVisited, result);
while (!result.isEmpty()) {
System.out.print(" " + result.pop());
}
}
private void topologicalSortRecursive(int current, boolean[] isVisited, Stack<Integer> result) {
isVisited[current] = true;
for (int dest : adjVertices.get(current)) {
if (!isVisited[dest])
topologicalSortRecursive(dest, isVisited, result);
}
result.push(current);
}
}

63
data-structures/src/main/java/com/baeldung/tree/BinaryTree.java
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@ -2,6 +2,7 @@ package com.baeldung.tree;
import java.util.LinkedList;
import java.util.Queue;
import java.util.Stack;
public class BinaryTree {
@ -147,6 +148,68 @@ public class BinaryTree {
}
}
public void traverseInOrderWithoutRecursion() {
Stack<Node> stack = new Stack<Node>();
Node current = root;
stack.push(root);
while(! stack.isEmpty()) {
while(current.left != null) {
current = current.left;
stack.push(current);
}
current = stack.pop();
System.out.print(" " + current.value);
if(current.right != null) {
current = current.right;
stack.push(current);
}
}
}
public void traversePreOrderWithoutRecursion() {
Stack<Node> stack = new Stack<Node>();
Node current = root;
stack.push(root);
while(! stack.isEmpty()) {
current = stack.pop();
System.out.print(" " + current.value);
if(current.right != null)
stack.push(current.right);
if(current.left != null)
stack.push(current.left);
}
}
public void traversePostOrderWithoutRecursion() {
Stack<Node> stack = new Stack<Node>();
Node prev = root;
Node current = root;
stack.push(root);
while (!stack.isEmpty()) {
current = stack.peek();
boolean hasChild = (current.left != null || current.right != null);
boolean isPrevLastChild = (prev == current.right || (prev == current.left && current.right == null));
if (!hasChild || isPrevLastChild) {
current = stack.pop();
System.out.print(" " + current.value);
prev = current;
} else {
if (current.right != null) {
stack.push(current.right);
}
if (current.left != null) {
stack.push(current.left);
}
}
}
}
class Node {
int value;
Node left;

37
data-structures/src/test/java/com/baeldung/graph/GraphUnitTest.java Normal file
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@ -0,0 +1,37 @@
package com.baeldung.graph;
import org.junit.Test;
public class GraphUnitTest {
@Test
public void givenDirectedGraph_whenDFS_thenPrintAllValues() {
Graph graph = createDirectedGraph();
graph.dfs(0);
System.out.println();
graph.dfsWithoutRecursion(0);
}
@Test
public void givenDirectedGraph_whenGetTopologicalSort_thenPrintValuesSorted() {
Graph graph = createDirectedGraph();
graph.topologicalSort(0);
}
private Graph createDirectedGraph() {
Graph graph = new Graph();
graph.addVertex(0);
graph.addVertex(1);
graph.addVertex(2);
graph.addVertex(3);
graph.addVertex(4);
graph.addVertex(5);
graph.addEdge(0, 1);
graph.addEdge(0, 2);
graph.addEdge(1, 3);
graph.addEdge(2, 3);
graph.addEdge(3, 4);
graph.addEdge(4, 5);
return graph;
}
}

6
data-structures/src/test/java/com/baeldung/tree/BinaryTreeUnitTest.java
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@ -87,6 +87,8 @@ public class BinaryTreeUnitTest {
BinaryTree bt = createBinaryTree();
bt.traverseInOrder(bt.root);
System.out.println();
bt.traverseInOrderWithoutRecursion();
}
@Test
@ -95,6 +97,8 @@ public class BinaryTreeUnitTest {
BinaryTree bt = createBinaryTree();
bt.traversePreOrder(bt.root);
System.out.println();
bt.traversePreOrderWithoutRecursion();
}
@Test
@ -103,6 +107,8 @@ public class BinaryTreeUnitTest {
BinaryTree bt = createBinaryTree();
bt.traversePostOrder(bt.root);
System.out.println();
bt.traversePostOrderWithoutRecursion();
}
@Test