advent-of-code-2024/3/task.ts

export async function solveTask3part1() {
    const decoder = new TextDecoder("utf-8");
    const inputData = await Deno.readFile('./3/input.txt');
    const input = decoder.decode(inputData);

    // console.log(input)

    let curStep = 0
    let step0Incr = ''
    let firstNumber:number|undefined = undefined;
    let secondNumber:number|undefined = undefined;
    const reset = () => {
        curStep = 0;
        step0Incr = '';
        firstNumber = undefined;
        secondNumber = undefined
    }

    const validOps = [];
    for (const char of input) {
        switch (curStep) {
            // 0: starts with 'mul('
            case 0: {
                if (char === 'mul('[step0Incr.length]) {
                    step0Incr += char;
                    if (step0Incr.length === 4) {
                        curStep = 1;
                    }
                } else {
                    reset()
                }
                break;
            }
            // 1: first number
            case 1: {
                if (firstNumber !== undefined && char === ',') {
                    curStep = 2;
                    break;
                }
                if ((firstNumber ?? 0).toString().length >= 3) {
                    reset();
                    break;
                }
                const intCurChar = parseInt(char);
                const firstNumberString = (firstNumber ?? 0).toString() + char;
                const temp_firstNumber = parseInt(firstNumberString);

                if (isNaN(intCurChar) || isNaN(temp_firstNumber)) {
                    reset();
                    break;
                }

                firstNumber = temp_firstNumber;
                break;
            }
            // 2: second number
            case 2: {
                if (firstNumber === undefined) throw new Error('firstNumber was undefined in Step 2?')
                if (secondNumber !== undefined && char === ')') {
                    validOps.push({ firstNumber, secondNumber });
                    reset();
                    break;
                }
                if ((secondNumber ?? 0).toString().length >= 3) {
                    reset();
                    break;
                }
                const intCurChar = parseInt(char);
                const secondNumberString = (secondNumber ?? 0).toString() + char;
                const temp_secondNumber = parseInt(secondNumberString);

                if (isNaN(intCurChar) || isNaN(temp_secondNumber)) {
                    reset();
                    break;
                }

                secondNumber = temp_secondNumber;
                break;
            }
            default: 
                break;
        }
        // console.log(char, step0Incr, firstNumber, secondNumber);
    }

    // console.log(validOps)

    const result = validOps
        .map( op => op.firstNumber * op.secondNumber)
        .reduce( (prev, cur) => prev + cur, 0)

    console.log('final result', result)
}

export async function solveTask3part2() {
    const decoder = new TextDecoder("utf-8");
    const inputData = await Deno.readFile('./3/input.txt');
    const input = decoder.decode(inputData);

    // console.log(input)

    let enabled = true;
    let enableIncr = '';
    let disableIncr = '';
    let curStep = 0
    let step0Incr = ''
    let firstNumber:number|undefined = undefined;
    let secondNumber:number|undefined = undefined;
    const reset = () => {
        curStep = 0;
        step0Incr = '';
        firstNumber = undefined;
        secondNumber = undefined
    }

    const validOps = [];
    for (const char of input) {
        if (char === 'do()'[enableIncr.length]) {
            enableIncr += char;
            if (enableIncr.length === 4) {
                enabled = true;
                enableIncr = '';
            }
        } else {
            enableIncr = '';
        }

        if (char === "don't()"[disableIncr.length]) {
            disableIncr += char;
            if (disableIncr.length === 6) {
                enabled = false;
                disableIncr = '';
            }
        } else {
            disableIncr = '';
        }

        if (!enabled) continue;
        switch (curStep) {
            // 0: starts with 'mul('
            case 0: {
                if (char === 'mul('[step0Incr.length]) {
                    step0Incr += char;
                    if (step0Incr.length === 4) {
                        curStep = 1;
                    }
                } else {
                    reset()
                }
                break;
            }
            // 1: first number
            case 1: {
                if (firstNumber !== undefined && char === ',') {
                    curStep = 2;
                    break;
                }
                if ((firstNumber ?? 0).toString().length >= 3) {
                    reset();
                    break;
                }
                const intCurChar = parseInt(char);
                const firstNumberString = (firstNumber ?? 0).toString() + char;
                const temp_firstNumber = parseInt(firstNumberString);

                if (isNaN(intCurChar) || isNaN(temp_firstNumber)) {
                    reset();
                    break;
                }

                firstNumber = temp_firstNumber;
                break;
            }
            // 2: second number
            case 2: {
                if (firstNumber === undefined) throw new Error('firstNumber was undefined in Step 2?')
                if (secondNumber !== undefined && char === ')') {
                    validOps.push({ firstNumber, secondNumber });
                    reset();
                    break;
                }
                if ((secondNumber ?? 0).toString().length >= 3) {
                    reset();
                    break;
                }
                const intCurChar = parseInt(char);
                const secondNumberString = (secondNumber ?? 0).toString() + char;
                const temp_secondNumber = parseInt(secondNumberString);

                if (isNaN(intCurChar) || isNaN(temp_secondNumber)) {
                    reset();
                    break;
                }

                secondNumber = temp_secondNumber;
                break;
            }
            default: 
                break;
        }
        // console.log(char, step0Incr, firstNumber, secondNumber);
    }

    console.log(validOps)

    const result = validOps
        .map( op => op.firstNumber * op.secondNumber)
        .reduce( (prev, cur) => prev + cur, 0)

    console.log('final result', result)
}