// Spiral: the first row plus a smaller

Question

// Spiral: the first row plus a smaller

spiral rotated 90 degrees clockwise
function spiral(lngRows, lngCols, nStart) {
return lngRows ? [range(nStart, (nStart + lngCols) - 1)].concat(
transpose(
spiral(lngCols, lngRows - 1, nStart + lngCols)
).map(reverse)
) : [
[]
];
}

// rows and columns transposed (for 90 degree rotation)
function transpose(lst) {
return lst.length > 1 ? lst[0].map(function (_, col) {
return lst.map(function (row) {
return row[col];
});
}) : lst;
}

// elements in reverse order (for 90 degree rotation)
function reverse(lst) {
return lst.length > 1 ? lst.reduceRight(function (acc, x) {
return acc.concat(x);
}, []) : lst;
}

// [m..n]
function range(m, n) {
return Array.apply(null, Array(n - m + 1)).map(function (x, i) {
return m + i;
});
}

// TESTING

var lstSpiral = spiral(n, n, 0);