Solve 2020/09

2020/09/example

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+576

2020/09/solution1.js

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+const { readInput } = require("./util");
+
+const { lines } = readInput("input");
+
+class Buffer {
+  constructor(size = 25) {
+    this.buffer = [];
+    this.size = size;
+  }
+
+  push(val) {
+    this.buffer.push(val);
+    if (this.buffer.length > this.size) {
+      this.buffer.shift();
+    }
+  }
+
+  isValid(val) {
+    if (this.buffer.length < this.size) {
+      return true;
+    }
+    for (let a = 0; a < this.buffer.length; a++) {
+      const wanted = val - this.buffer[a];
+      for (let b = a + 1; b < this.buffer.length; b++) {
+        if (this.buffer[b] === wanted) {
+          return true;
+        }
+      }
+    }
+    return false;
+  }
+}
+
+const buffer = new Buffer(25);
+
+for (const line of lines) {
+  const val = parseInt(line);
+  console.log(buffer.buffer, val, buffer.isValid(val));
+  if (!buffer.isValid(val)) {
+    console.log(val);
+    break;
+  }
+  buffer.push(parseInt(line));
+}

2020/09/solution2.js

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+const { readInput } = require("./util");
+
+const { lines } = readInput("input");
+
+class Buffer {
+  constructor(size = 25) {
+    this.buffer = [];
+    this.size = size;
+  }
+
+  push(val) {
+    this.buffer.push(val);
+    if (this.buffer.length > this.size) {
+      this.buffer.shift();
+    }
+  }
+
+  isValid(val) {
+    if (this.buffer.length < this.size) {
+      return true;
+    }
+    for (let a = 0; a < this.buffer.length; a++) {
+      const wanted = val - this.buffer[a];
+      for (let b = a + 1; b < this.buffer.length; b++) {
+        if (this.buffer[b] === wanted) {
+          return true;
+        }
+      }
+    }
+    return false;
+  }
+}
+
+let weakness = null;
+const buffer = new Buffer(25);
+for (const line of lines) {
+  const val = parseInt(line);
+  // console.log(buffer.buffer, val, buffer.isValid(val));
+  if (!buffer.isValid(val)) {
+    weakness = val;
+    break;
+  }
+  buffer.push(parseInt(line));
+}
+
+const stream = lines.map((line) => parseInt(line));
+
+let lower = 0;
+let upper = 0;
+let sum = stream[0];
+
+while (sum !== weakness && lower < stream.length) {
+  while (sum > weakness) {
+    sum -= stream[upper];
+    upper--;
+  }
+  while (sum < weakness) {
+    upper++;
+    sum += stream[upper];
+  }
+  sum -= stream[lower];
+  lower++;
+}
+
+const range = stream.slice(lower, upper + 1);
+const [min, max] = [Math.min(...range), Math.max(...range)];
+console.log({ lower, upper, range, min, max });
+
+console.log("Solution:");
+console.log(min + max);

2020/09/util.js

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+const fs = require("fs");
+
+exports.readInput = function (filename = "input") {
+  const input = fs.readFileSync(filename, "utf-8").trim();
+  const lines = input.split("\n");
+  const paragraphs = input.split("\n\n");
+
+  let colLength = lines[0].length;
+  let colConsistentcy = true;
+  for (const line of lines) {
+    if (colLength != line.length) {
+      colConsistentcy = false;
+    }
+  }
+
+  const avgLength = sum(lines.map((l) => l.length)) / lines.length;
+
+  console.log("Number of lines:", lines.length);
+  console.log("Number of paragraphs", paragraphs.length);
+  console.log("Col-length is consistent:", colConsistentcy);
+  console.log("Average col-length", avgLength);
+
+  console.log("Sample:");
+  for (const line of lines.slice(0, 5)) {
+    console.log(line);
+  }
+  console.log("...");
+  for (const line of lines.slice(lines.length - 5, lines.length)) {
+    console.log(line);
+  }
+  console.log("=".repeat(process.stdout.columns));
+
+  return {
+    raw: input,
+    lines,
+    paragraphs,
+  };
+};
+
+const sum = (arr) => arr.reduce((a, b) => a + b, 0);
+exports.sum = sum;