From 27cd471ef172362cfdf8621c0c9a1c4edd35863e Mon Sep 17 00:00:00 2001
From: Michael Hunteman <michael@huntm.net>
Date: Sat, 1 Oct 2022 18:15:49 -0500
Subject: Add Number of Islands

---
 CourseSchedule.java  | 46 +++++++++++++++++++++++-----------------------
 NumberOfIslands.java | 38 ++++++++++++++++++++++++++++++++++++++
 2 files changed, 61 insertions(+), 23 deletions(-)
 create mode 100644 NumberOfIslands.java

diff --git a/CourseSchedule.java b/CourseSchedule.java
index 5b5ed02..6f85f44 100644
--- a/CourseSchedule.java
+++ b/CourseSchedule.java
@@ -3,9 +3,26 @@ import java.util.*;
 import node.*;
 
 class CourseSchedule {
-	public static boolean canFinish(int[][] prerequisites) {
-		GraphNode node = createGraph(prerequisites);
-		return !detectCycle(node);
+	public static boolean detectCycle(GraphNode node) {
+		Stack<GraphNode> stack = new Stack<GraphNode>();
+		ArrayList<GraphNode> visited = new ArrayList<GraphNode>();
+		stack.push(node);
+		while (!stack.empty()) {
+			node = stack.pop();
+			if (visited.contains(node)) {
+				System.out.println("Cycle " + node.val);
+				return true;
+			}
+			visited.add(node);
+			System.out.println("Node: " + node.val);
+			System.out.print("Neighbors: ");
+			for (GraphNode neighbor : node.neighbors) {
+				stack.push(neighbor);
+				System.out.print(neighbor.val + " ");
+			}
+			System.out.println();
+		}
+		return false;
 	}
 
 	public static GraphNode createGraph(int[][] prerequisites) {
@@ -31,26 +48,9 @@ class CourseSchedule {
 		return map.get(1);
 	}
 
-	public static boolean detectCycle(GraphNode node) {
-		Stack<GraphNode> stack = new Stack<GraphNode>();
-		ArrayList<GraphNode> visited = new ArrayList<GraphNode>();
-		stack.push(node);
-		while (!stack.empty()) {
-			node = stack.pop();
-			if (visited.contains(node)) {
-				System.out.println("Cycle " + node.val);
-				return true;
-			}
-			visited.add(node);
-			System.out.println("Node: " + node.val);
-			System.out.print("Neighbors: ");
-			for (GraphNode neighbor : node.neighbors) {
-				stack.push(neighbor);
-				System.out.print(neighbor.val + " ");
-			}
-			System.out.println();
-		}
-		return false;
+	public static boolean canFinish(int[][] prerequisites) {
+		GraphNode node = createGraph(prerequisites);
+		return !detectCycle(node);
 	}
 
 	public static void main(String[] args) {
diff --git a/NumberOfIslands.java b/NumberOfIslands.java
new file mode 100644
index 0000000..422b80e
--- /dev/null
+++ b/NumberOfIslands.java
@@ -0,0 +1,38 @@
+import java.lang.*;
+import java.util.*;
+
+class NumberOfIslands {
+	public static void setZero(int y, int x, int[][] grid) {
+		if (y < 0 || y > grid.length - 1 || x < 0 || x > grid[0].length - 1 || grid[y][x] == 0)
+			return;
+		grid[y][x] = 0;
+		System.out.println("y: " + y + " x: " + x);
+		setZero(y, x + 1, grid);
+		setZero(y + 1, x, grid);
+		setZero(y, x - 1, grid);
+		setZero(y - 1, x, grid);
+	}
+
+	public static int numIslands(int[][] grid) {
+		int num = 0;
+		for (int y = 0; y < grid.length; y++) {
+			for (int x = 0; x < grid[y].length; x++) {
+				if (grid[y][x] == 1) {
+					num++;
+					setZero(y, x, grid);
+				}
+			}
+		}
+		return num;
+	}
+
+	public static void main(String[] args) {
+		int[][] grid = {
+		  {1,1,1,1,0},
+		  {1,1,0,1,0},
+		  {1,1,0,0,0},
+		  {0,0,0,1,1}
+		};
+		System.out.println(numIslands(grid));
+	}
+}
-- 
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