From b13e847401578abb66bb32e495db5518f3e5caf7 Mon Sep 17 00:00:00 2001
From: David Ashby <delta.mu.alpha@gmail.com>
Date: Thu, 4 Dec 2025 22:30:22 -0500
Subject: [PATCH] use reducers instead of foreach

---
 src/Day04.java | 41 +++++++++++++++--------------------------
 1 file changed, 15 insertions(+), 26 deletions(-)

diff --git a/src/Day04.java b/src/Day04.java
index 092f9e9..967d771 100644
--- a/src/Day04.java
+++ b/src/Day04.java
@@ -9,10 +9,9 @@ import java.util.Scanner;
 
 public class Day04 {
 
-    private static int neighbors = 0;
     private static int score = 0;
     private static int round = 0;
-    private static Map<String, Boolean> floor = new java.util.HashMap<>();
+    private static Map<String, Integer> floor = new java.util.HashMap<>();
 
     public static void main(String[] args) {
         Instant start = Instant.now();
@@ -37,25 +36,20 @@ public class Day04 {
                 for (int i = 0; i < size; i++) {
                     String key = "%s-%s".formatted(i, rowIndex);
                     if (row[i].equals("@")) {
-                        floor.put(key, true);
-                    } else {
-                        floor.put(key, false);
+                        floor.put(key, 1);
                     }
-
                 }
                 rowIndex++;
             }
             floor.forEach((key, value) -> {
-                if (value) {
+                if (value == 1) {
                     String[] coords = key.split("-");
                     int x = Integer.parseInt(coords[0]);
                     int y = Integer.parseInt(coords[1]);
-                    neighbors = 0;
-                    generateNeighborKeys(x, y).forEach((coord) -> {
-                        if (floor.getOrDefault(coord, false)) {
-                            neighbors += 1;
-                        }
-                    });
+                    int neighbors = generateNeighborKeys(x, y).stream().reduce(
+                            0,
+                            (t, coord) -> (t + floor.getOrDefault(coord, 0)),
+                            Integer::sum);
                     if (neighbors < 4) {
                         score += 1;
                     }
@@ -79,30 +73,25 @@ public class Day04 {
                 for (int i = 0; i < size; i++) {
                     String key = "%s-%s".formatted(i, rowIndex);
                     if (row[i].equals("@")) {
-                        floor.put(key, true);
-                    } else {
-                        floor.put(key, false);
+                        floor.put(key, 1);
                     }
-
                 }
                 rowIndex++;
             }
             while (true) {
-                Map<String, Boolean> newFloor = new java.util.HashMap<>(floor);
+                Map<String, Integer> newFloor = new java.util.HashMap<>(floor);
                 floor.forEach((key, value) -> {
-                    if (value) {
+                    if (value == 1) {
                         String[] coords = key.split("-");
                         int x = Integer.parseInt(coords[0]);
                         int y = Integer.parseInt(coords[1]);
-                        neighbors = 0;
-                        generateNeighborKeys(x, y).forEach((coord) -> {
-                            if (floor.getOrDefault(coord, false)) {
-                                neighbors += 1;
-                            }
-                        });
+                        int neighbors = generateNeighborKeys(x, y).stream().reduce(
+                                0,
+                                (t, coord) -> (t + floor.getOrDefault(coord, 0)),
+                                Integer::sum);
                         if (neighbors < 4) {
                             round += 1;
-                            newFloor.put(key, false);
+                            newFloor.put(key, 0);
                         }
                     }
                 });