希尔排序（基于插入排序）

提供一个h，调整插入排序的间隔，直到h降级为1，变成插入排序

const { less, exch } = require('./util');
const arr1 = [2,3,1,123,5,24]
function shell(arr) {
    let N = arr.length;
    let h = 1;
    while(h < (N / 3)) h = 3 * h + 1;
    while(h !== 0) {
        for (let i = h; i < N; i++) {
            for (j = i; j >= h && less(arr[j], arr[j - h]); j -= h) {
                exch(arr, j, j - h);
            }
        }
        h = Math.floor(h / 3);
    }
    return arr;
}
console.log(shell(arr1));