Function power

javascript/0070-climbing-stairs.js:126–143

(n, prev)

};

const power = (n, prev) => {
    let next = [
        [1, 0],
        [0, 1],
    ];

    const isEmpty = () => n === 0;
    while (!isEmpty()) {
        /* Time O(log(N)) */
        const isBit = (n & 1) === 1;
        if (isBit) next = multiply(next, prev); /* Time O(1) | Space O(1) */

        n >>= 1;
        prev = multiply(prev, prev); /* Time O(1) | Space O(1) */
    }

    return next;
};

const multiply = (prev, next) => {
    const [rows, cols] = [2, 2];