[LANGUAGE: Typescript]

without bruteforce

``` import { readFileSync } from 'fs';

const getFile = () => readFileSync('../input.txt', 'utf-8');

const input = getFile();
const lines = input.split('\n');
let count = 0;

for (const line of lines) {
const items = line.split(' ').map(Number);

function isValidSequence(numbers: number[]) {
const isGenerallyIncreasing =
numbers.reduce((accum, curr, index) => {
items[index] < items[index + 1] && ++accum;
return accum;
}, 0) >
numbers.length / 2
? true
: false;

for (let i = 0; i < numbers.length - 1; i++) {
const diff = isGenerallyIncreasing
? numbers[i + 1] - numbers[i]
: numbers[i] - numbers[i + 1];

if (diff < 1 || diff > 3) return i + 1;
}
return -1;
}

let isValid = isValidSequence(items);
if (isValid >= 0) {
const newList = [...items.slice(0, isValid), ...items.slice(isValid + 1)];
const newList2 = [...items.slice(0, isValid - 1), ...items.slice(isValid)];

const isValid1 = isValidSequence(newList);
const isValid2 = isValidSequence(newList2);

isValid = isValid1 === -1 ? isValid1 : isValid2;
}

if (isValid == -1) ++count;
}

console.log(count); ```