From fe806f4400df930c819d76df87e75bfbafd968fd Mon Sep 17 00:00:00 2001
From: x0x7 <x0x7@tutanota.com>
Date: Wed, 4 Dec 2024 17:33:28 -0500
Subject: [PATCH] Add 2024/day4/part1.js

---
 2024/day4/part1.js | 125 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 125 insertions(+)
 create mode 100644 2024/day4/part1.js

diff --git a/2024/day4/part1.js b/2024/day4/part1.js
new file mode 100644
index 0000000..ae476e0
--- /dev/null
+++ b/2024/day4/part1.js
@@ -0,0 +1,125 @@
+#!/usr/bin/env node
+
+
+var input = require('fs').readFileSync(process.argv[2]||'input.txt','utf8').split('\n').filter(i=>i);
+//Make many versions of the data in different orientations
+//All modes are an array of buffers.  We will turn them into arrays of strings soon.
+var mode0 = input.map(i=>Buffer.from(i));
+//Width and height happen to be equal.. 140
+var width = mode0[0].length;
+var height = mode0.length;
+//Transpose mode1
+var mode1 = [];
+for(var i=0;i<width;++i) { //Allocate
+ mode1.push(Buffer.alloc(height));
+}
+for(var i=0;i<height;++i) {
+ for(var j=0;j<width;++j) {
+  mode1[j][i]=mode0[i][j];
+ }
+}
+//Diaganal mode2
+var mode2 = [];
+for(var i=1;i<=width;++i) { //Allocate half
+ mode2.push(Buffer.alloc(i));
+}
+for(var i=width-1;i>0;--i) { //Allocate second half
+ mode2.push(Buffer.alloc(i));
+}
+var ri=0;
+var rj=0;
+var wi=0;
+var wj=0;
+try {
+ while(true) {
+  mode2[wi][wj]=mode0[ri][rj];
+  --ri;
+  ++rj;
+  ++wj;
+  if(mode2[wi].length==wj) { //This bit is simple
+   ++wi;
+   wj=0;
+  }
+  if(ri<0) {
+   ri=rj
+   rj=0;
+  }
+  if(rj>=mode0.length) {
+   ++ri; //Reverse
+   --rj; //Reverse
+   ++ri; //Go down one
+   //Swap ri and rj
+   var temp=ri;
+   ri=rj;
+   rj=temp;
+  }
+  if(ri>=mode0.length) {
+   rj=(ri-(mode0.length-1));
+   ri=mode0.length-1;
+  }
+ }
+} catch(e) {
+ //console.log('error',{ri,rj,wi,wj});
+ //Let it run.  When we have an error we did the job
+}
+
+//Diagonal mode3
+var mode3 = [];
+for(var i=1;i<=width;++i) { //Allocate half
+ mode3.push(Buffer.alloc(i));
+}
+for(var i=width-1;i>0;--i) { //Allocate second half
+ mode3.push(Buffer.alloc(i));
+}
+var ri=0;
+var rj=width-1;
+var wi=0;
+var wj=0;
+try {
+ while(true) {
+  //console.log({ri,rj});
+  mode3[wi][wj]=mode0[ri][rj];
+  ++ri;
+  ++rj;
+  ++wj;
+  if(mode3[wi].length==wj) { //This bit is simple
+   ++wi;
+   wj=0;
+  }
+  if(rj>=width) {
+   --ri;//Reverse
+   --rj;//Reverse
+   ++ri;//Get on new diaganol
+   rj=width-ri-1; // Go to other side of diaganol
+   ri=0; // Go to other side of diaganol
+  }
+  if(rj<0) {
+   ri=-rj;
+   rj=0;
+  }
+  if(ri>=width) {
+   --ri;//Reverse
+   --rj;//Reverse
+   --rj;//Get on new diaganol
+   ri=width-1-rj;
+   rj=0;
+  }
+  if(ri<0 || ri>=width || rj<0 || rj>=width) throw 'Out of bounds';
+ }
+} catch(e) {
+ //console.log('Error mode3:',{ri,rj,wi,wj});
+ //Continue, it is filled;
+}
+
+
+var modes = [mode0,mode1,mode2,mode3].map(i=>i.map(i=>i.toString())); //Convert all into strings
+var regex1 = /XMAS/g
+var regex2 = /SAMX/g
+
+var sum = modes.reduce((acc1,grid)=>acc1+grid.reduce((acc2,line)=>{
+ var match1 = line.match(regex1);
+ var match2 = line.match(regex2);
+ return acc2 + (match1?match1.length:0) + (match2?match2.length:0);
+},0),0);
+
+console.log('Result:',sum);
\ No newline at end of file