Add day 10 part 1

Author: lundgren2

src/2020/day10/input

@@ -0,0 +1,97 @@
+8
+131
+91
+35
+47
+116
+105
+121
+56
+62
+94
+72
+13
+82
+156
+102
+12
+59
+31
+138
+46
+120
+7
+127
+126
+111
+2
+123
+22
+69
+18
+157
+75
+149
+88
+81
+23
+98
+132
+1
+63
+142
+37
+133
+61
+112
+122
+128
+155
+145
+139
+66
+42
+134
+24
+60
+9
+28
+17
+29
+101
+148
+96
+68
+25
+19
+6
+67
+113
+55
+40
+135
+97
+79
+48
+159
+14
+43
+86
+36
+41
+85
+87
+119
+30
+108
+80
+152
+158
+151
+32
+78
+150
+95
+3
+52
+49

src/2020/day10/part1.ts

@@ -0,0 +1,14 @@
+export const part1 = (input: string) => {
+  const joltage = [0, ...input.split('\n')].map(Number).sort((a, b) => a - b);
+
+  let oneDiff = 0;
+  let threeDiff = 1; // 3 higher than the highest-rated adapter.
+
+  joltage.forEach((current, i) => {
+    const diff = joltage[i + 1] - current;
+    if (diff === 1) oneDiff++;
+    else if (diff === 3) threeDiff++;
+  });
+
+  return oneDiff * threeDiff;
+};

src/2020/day10/test.spec.ts

@@ -0,0 +1,66 @@
+import {readInput} from '../../utils';
+
+import {part1} from './part1';
+
+describe('Advent of Code 2020 - Day 10', () => {
+  let input: string;
+  const testInput = `28
+33
+18
+42
+31
+14
+46
+20
+48
+47
+24
+23
+49
+45
+19
+38
+39
+11
+1
+32
+25
+35
+8
+17
+7
+9
+4
+2
+34
+10
+3`;
+
+  beforeAll(async () => {
+    input = await readInput(__dirname + '/input');
+  });
+
+  describe('part 1', () => {
+    it('should output 7*5', () => {
+      const input = `16
+10
+15
+5
+1
+11
+7
+19
+6
+12
+4`;
+      expect(part1(input)).toBe(7 * 5);
+    });
+    it('should output 22*10 ', () => {
+      expect(part1(testInput)).toBe(22 * 10);
+    });
+
+    it('should output 2112 from input', () => {
+      expect(part1(input)).toBe(2112);
+    });
+  });
+});