cassidoo_dec_22_2025_1.js

/* solution */

function process([y, z, ...rest] = []) {
    while (rest.length) {
        if (rest.shift() !== y) return false;
        [z, y] = [y, z];
    }
    return true;
}    



/* testing */

function assert(input, expected) {

    const actual = process(input);
    if (actual !== expected)
        console.error("FAIL", input, "(expected", expected, ")");
    else
        console.log("PASS", input);

}

assert([], true);
assert([1], true);
assert([1,1], true);
assert([1,2,1], true);
assert([10,5,10,5,10], true);
assert([2,2,3,3], false);
assert([5,4,3,5,4,3], false);