Chapter 19 method stubs and descriptions + new data structure

Author: gardncl

datastructures/src/main/java/GraphVertex.java

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+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+
+public class GraphVertex {
+    public int label;
+    public List<GraphVertex> edges;
+    public boolean visited;
+
+    public GraphVertex(int label) {
+        this.label = label;
+        this.edges = new ArrayList<>();
+        this.visited = false;
+    }
+
+    public GraphVertex(int label, GraphVertex... graphVertices) {
+        this.label = label;
+        this.edges = Arrays.asList(graphVertices);
+        this.visited = false;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+
+        GraphVertex that = (GraphVertex) o;
+
+        if (label != that.label) return false;
+        return edges != null ? edges.equals(that.edges) : that.edges == null;
+    }
+}

graphs/README.md

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+# Chapter 19: Graphs
+
+* 19.1 SearchMaze
+* 19.2 PaintBooleanMatrix
+* 19.3 ComputeEnclosedRegions
+* 19.4 DeadlockDetection
+* 19.5 CloneAGraph
+* 19.6 MakingWiredConnections
+* 19.7 TransformOneStringToAnother
+* 19.8 TeamPhotoDay
+* 19.9 ComputeShortestPath

graphs/pom.xml

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+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <parent>
+        <artifactId>elements-of-programming-interviews</artifactId>
+        <groupId>gardncl</groupId>
+        <version>1.0</version>
+    </parent>
+    <modelVersion>4.0.0</modelVersion>
+
+    <artifactId>graphs</artifactId>
+    <name>Chapter 19: Graphs</name>
+    <dependencies>
+        <dependency>
+            <groupId>gardncl</groupId>
+            <artifactId>datastructures</artifactId>
+            <version>1.0</version>
+        </dependency>
+    </dependencies>
+
+
+</project>

graphs/src/main/java/CloneAGraph.java

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+public class CloneAGraph {
+
+    /*
+    19.5
+
+    Consider a vertex type for a directed graph in which there
+    are two fields: an integer label and a list of references
+    to other vertices. Design an algorithm that takes a reference
+    to a vertex u, and creates a copy of the graph on the vertices
+    reachable from u. Return the copy of u.
+     */
+
+    public static GraphVertex cloneGraph(GraphVertex g) {
+
+        return new GraphVertex(0);
+    }
+}

graphs/src/main/java/ComputeEnclosedRegions.java

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+import java.util.List;
+
+public class ComputeEnclosedRegions {
+
+    /*
+    19.3
+
+    Let A by a 2D array whose entries are either W or B.
+    Write a program that takes A, and replaces all Ws
+    that cannot reach the boundary with a B.
+     */
+
+    public static void fillSurroundingRegions(List<List<Character>> board) {
+
+    }
+}

graphs/src/main/java/ComputeShortestPath.java

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+public class ComputeShortestPath {
+
+    /*
+    19.9
+
+    Design an algorithm which takes as input a graph G = (V,E),
+    directed or undirected, a non-negative cost function on E,
+    and vertices s and t; your algorithm should output a path
+    with the fewest edges amongst all shortest paths from s to t.
+     */
+
+    public static void compute(GraphVertex s, GraphVertex t) {
+
+    }
+}

graphs/src/main/java/DeadlockDetection.java

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+import java.util.List;
+
+public class DeadlockDetection {
+
+    /*
+    19.4
+
+    Write a program that takes as input a directed graph
+    and checks if the graph contains a cycle.
+     */
+
+    public static class ColoredGraphVertex {
+        public static enum Color {WHITE, GRAY, BLACK}
+
+        public Color color;
+        public List<ColoredGraphVertex> edges;
+    }
+
+    public static boolean isDeadlocked(List<ColoredGraphVertex> G) {
+
+        return false;
+    }
+}

graphs/src/main/java/MakingWiredConnections.java

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+import java.util.List;
+
+public class MakingWiredConnections {
+
+    /*
+    19.6
+
+    Design an algorithm that takes a set of pins and a set of wires
+    connecting pairs of pins, and determines if it is possible to
+    place some pins on the left half of a PCB, and the remainder on
+    the right half, such that each wire is between left and right
+    halves.
+     */
+
+    public static boolean isAnyPlacementFeasible(List<GraphVertex> G) {
+
+        return false;
+    }
+}

graphs/src/main/java/PaintBooleanMatrix.java

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+import java.util.List;
+
+public class PaintBooleanMatrix {
+
+    /*
+    19.2
+
+    Implement a routine that takes an n x m Boolean array A
+    together with an entry (x,y) and flips the color of the
+    region associated with (x,y).
+     */
+
+    public static void flipColor(List<List<Boolean>> A, int x, int y) {
+
+    }
+}

graphs/src/main/java/SearchMaze.java

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+import java.util.Collections;
+import java.util.List;
+
+public class SearchMaze {
+
+    /*
+    19.1
+
+    Given a 2D array of black and white entries representing
+    a maze with designated entrance and exit points, find a
+    path from the entrance to teh exit, if one exists.
+     */
+
+    public static enum Color {WHITE, BLACK}
+
+    public static List<Tuple> searchMaze(List<List<Color>> maze, Tuple s, Tuple e) {
+
+        return Collections.emptyList();
+    }
+}