插入排序

func insertionSort(array []int) {
    for i := 1; i < len(array); i++ {
        key := array[i]
        j := i - 1
        for j >= 0 && array[j] > key {
            array[j+1] = array[j]
            j--
        }
        array[j+1] = key
    }
}

第5行先判断j是否大于等于0防止切片下标越界