advent-of-code

commit c0062bef3c1e6590e98178ed81b22f2853a68ef0
parent 0d285583cd7eb162ccef53ae20164af6685ac9d3
Author: finwo <finwo@pm.me>
Date:   Wed, 14 Dec 2022 10:02:10 +0100

2022/14 solution

Diffstat:
A
2022/day-14/index.js
 | 
202
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
A
2022/day-14/sample
 | 
2
++

2 files changed, 204 insertions(+), 0 deletions(-)
diff --git a/2022/day-14/index.js b/2022/day-14/index.js
@@ -0,0 +1,202 @@
+const fs           = require('fs');
+const through      = require('through2');
+const line_by_line = require('../common/line-for-line');
+
+String.prototype.startsWith = function(subject) {
+  return this.substr(0, subject.length) === subject;
+};
+
+const grid       = [];
+const entryPoint = [500, 0];
+
+function range(start, end) {
+  const ret = [];
+  const high = Math.max(start, end);
+  const low  = Math.min(start, end);
+  for(let i=low; i<=high; i++) ret.push(i);
+  return low == start ? ret : ret.reverse();
+}
+
+function plot(x, y, value = 1) {
+  grid[y] = grid[y] || [];
+  grid[y][x] = value;
+}
+
+// Pulled straight out of wikipedia
+function plotLineLow(x0, y0, x1, y1) {
+    let dx = x1 - x0;
+    let dy = y1 - y0;
+    let yi = 1;
+    if (dy < 0) {
+        yi = -1;
+        dy = -dy;
+    }
+    let D = (2 * dy) - dx;
+    let y = y0;
+    for (const x of range(x0, x1)) {
+        plot(x, y);
+        if (D > 0) {
+            y = y + yi;
+            D = D + (2 * (dy - dx));
+        } else {
+            D = D + 2*dy;
+        }
+    }
+}
+function plotLineHigh(x0, y0, x1, y1) {
+    let dx = x1 - x0;
+    let dy = y1 - y0;
+    let xi = 1;
+    if (dx < 0) {
+        xi = -1;
+        dx = -dx;
+    }
+    let D = (2 * dx) - dy;
+    let x = x0;
+    for (const y of range(y0, y1)) {
+        plot(x, y);
+        if (D > 0) {
+            x = x + xi;
+            D = D + (2 * (dx - dy));
+        } else {
+            D = D + 2*dx;
+        }
+    }
+}
+function plotLine(x0, y0, x1, y1) {
+  if (Math.abs(y1 - y0) < Math.abs(x1 - x0)) {
+    if (x0 > x1) {
+      plotLineLow(x1, y1, x0, y0)
+    } else {
+      plotLineLow(x0, y0, x1, y1)
+    }
+  } else {
+    if (y0 > y1) {
+      plotLineHigh(x1, y1, x0, y0)
+    } else {
+      plotLineHigh(x0, y0, x1, y1)
+    }
+  }
+}
+
+let minx = entryPoint[0];
+let maxx = entryPoint[0];
+let miny = entryPoint[1];
+let maxy = entryPoint[1];
+
+function drawArea() {
+  // Draw area
+  for(let y=miny; y<=maxy; y++) {
+    for(let x=minx; x<=maxx; x++) {
+      if (grid[y] && grid[y][x] == 1) {
+        process.stdout.write('#');
+      } else if (grid[y] && grid[y][x] == 2) {
+        process.stdout.write('+');
+      } else if (grid[y] && grid[y][x] == 3) {
+        process.stdout.write('o');
+      } else {
+        process.stdout.write('.');
+      }
+    }
+    process.stdout.write('\n');
+  }
+}
+
+
+
+let units = 0;
+
+fs.createReadStream('input')
+  .pipe(line_by_line())
+
+  // Minor parsing
+  .pipe(through(function(line, enc, cb) {
+    line = line.toString();
+
+    // Turn into line point coordinates
+    const points = line
+      .split(' -> ')
+      .map(point => point.split(',').map(a => parseInt(a)));
+
+    // Track range to visualize later
+    points.forEach(point => {
+      minx = Math.min(minx, point[0]);
+      miny = Math.min(miny, point[1]);
+      maxx = Math.max(maxx, point[0]);
+      maxy = Math.max(maxy, point[1]);
+    });
+
+    // "draw" lines
+    let lastPoint = points.shift();
+    while(points.length) {
+      const point = points.shift();
+      plotLine(
+        lastPoint[0], lastPoint[1],
+        point[0], point[1],
+      );
+      lastPoint = point;
+    }
+
+    cb();
+  }))
+
+  .on('finish', () => {
+
+    // Mark entrypoint
+    plot(entryPoint[0], entryPoint[1], 2);
+
+    // Mark floor
+    maxy+=2;
+    plotLine(
+      minx-10000, maxy,
+      maxx+10000, maxy,
+    );
+    minx -= 10;
+    maxx += 10;
+
+    // Let sand fall in
+    while(true) {
+
+      let unit = [...entryPoint];
+
+      while(true) {
+        if (unit[1] > maxy) {
+          break;
+        }
+        if (!(grid[unit[1]+1])) {
+          unit[1]++;
+        } else if (!(grid[unit[1]+1][unit[0]])) {
+          unit[1]++;
+        } else if (!(grid[unit[1]+1][unit[0]-1])) {
+          unit[0]--;
+          unit[1]++;
+        } else if (!(grid[unit[1]+1][unit[0]+1])) {
+          unit[0]++;
+          unit[1]++;
+        } else {
+          // rest
+          break;
+        }
+      }
+
+      plot(unit[0], unit[1], 3);
+      units++;
+
+      if (units%100 == 0) {
+        drawArea();
+        process.stdout.write('\n'.repeat(3));
+      }
+
+      if (
+        (unit[1] > maxy) ||
+        (unit[0] == entryPoint[0] && unit[1] == entryPoint[1])
+      ) {
+        break;
+      }
+    }
+
+
+    drawArea();
+    console.log({ units });
+    console.log('finish');
+  });
diff --git a/2022/day-14/sample b/2022/day-14/sample
@@ -0,0 +1,2 @@
+498,4 -> 498,6 -> 496,6
+503,4 -> 502,4 -> 502,9 -> 494,9