构建数组

网上的tx面试题：输入n，输出方阵：
n=5时如下:

0   0   0   0   5   
0   0   0   6   4   
0   0   7   14  3
0   8   15  13  2
9   10  11  12  1

n=3时如下:

0   0   3
0   4   2
5   6   1

代码：

package main

import (
    "fmt"
)

func main() {
    /*
       输入n，输出方阵，
       n=6时如下
       0   0   0   0   0   6
       0   0   0   0   7   5
       0   0   0   8   18  4
       0   0   9   19  17  3
       0   10  20  21  16  2
       11  12  13  14  15  1
       n=3时如下
       0   0   3
       0   4   2
       5   6   1
    */
    n := 6
    res := getres(n)
    for i := 0; i < len(res); i++ {
        fmt.Println(res[i])
    }
}

func getres(n int) [][]int {
    matrix := make([][]int, n)
    for i := 0; i < n; i++ {
        matrix[i] = make([]int, n)
    }
    direction := 0
    idx := 1
    left := 0
    right := n - 1

    low := 0
    high := n - 1

    final := n * (n + 1) / 2
    fmt.Println(final)
    for idx <= final {
        switch direction % 3 {
        case 0: //下->上
            for i := high; i >= low; i-- {
                matrix[i][right] = idx
                idx += 1
            }
            right -= 1
            low += 1
        case 1: //右上->左下
            for i, j := low, right; i <= high && j >= left; i, j = i+1, j-1 {
                matrix[i][j] = idx
                idx += 1
            }
            low += 1
            left += 1
        case 2: //左->右
            for j := left; j <= right; j++ {
                matrix[high][j] = idx
                idx += 1
            }
            high -= 1
            left += 1
        }
        direction += 1
    }
    return matrix
}

output:

[0  0   0  0  0  6]
[0  0   0  0  7  5]
[0  0   0  8  18 4]
[0  0   9  19 17 3]
[0  10  20 21 16 2]
[11 12  13 14 15 1]