Everest

РЕШЕНИЕ С FOR:

function everest(input) {
    let start = 5364;
    let days = 1;

    for (let i = 0; i < input.length; i++) {
        let sleep = input[i++];
        if (sleep === "END") {
            break;
        } else if (sleep === "Yes") {
            days++;
            if (days === 6) {
                break;
            }
        }
        start += Number(input[i]);
        if (start >= 8848) {
            break;
        }
    }

    if (start < 8848) {
        console.log(`Failed!\n${start}`)
    } else {
        console.log(`Goal reached for ${days} days!`);
    }
}

РЕШЕНИЕ С WHILE, SHIFT() И ТЕРНАРЕН ОПЕРАТОР:

function everest(input) {
    let start = 5364;
    let days = 1;

    while (days !== 6 && input[0] !== "END" && start < 8848) {
        days += input.shift() === "Yes" ? 1 : 0;
        start += Number(input.shift());
    }

    console.log(start < 8848 ? `Failed!\n${start}` : `Goal reached for ${days} days!`);
}