function insertionSort1(n: number, arr: number[]): void {
    /**
     * simple as question requested.
     * 
     * + number [i] store index of arr
     * + number [x] store sorting element
     * 
     * index [i] move from end of [arr] to 0, check previous element [i - 1] is 
     * lower than [x] then replace [arr][i] by [x] then stop
     * orelse keep moving [index] replace current [arr][i] by [i - 1]
     */
    let i = arr.length - 1
    let x = arr[i]

    while (x != 0) {
        if ((arr[i - 1] ?? 0) < x) {
            arr[i] = x
            x = 0
        } else {
            arr[i] = arr[i - 1]
            i--
        }
        console.log(arr.join(' '))
    }
}