在go中对角迭代整数的二维切片

Question

什么是对角地遍历整数的二维切片的惯用方式。是负对角线还是正对角线？

这是一个带有 2d 网格设置的游乐场。 https://go.dev/play/p/Cpxg4a5HvrD

Answer 1

如果x == y，或者在本例中为i == j，那么它就是对角线。

func main() {
    size := 4
    board := make([][]int, size)
    for i := range board {
        board[i] = append(board[i], make([]int, size)...)
    }
    for i, row := range board {
        for j := range row {
            board[i][j] = rand.Intn(9)
            if i == j {
                log.Println("diagonal:", board[i][j])
            }
        }
    }
    for _, row := range board {
        fmt.Println(row)
    }
}

那会打印出来

2021/12/21 01:33:59 diagonal: 5
2021/12/21 01:33:59 diagonal: 6
2021/12/21 01:33:59 diagonal: 5
2021/12/21 01:33:59 diagonal: 8
[5 6 2 2]
[4 6 7 8]
[4 6 5 7]
[3 2 4 8]

如果你想要不同的对角线，你可以偏移其中一个轴，例如x == y+1，或i == j+1

那会打印出来

2021/12/21 01:38:07 diagonal: 4
2021/12/21 01:38:07 diagonal: 6
2021/12/21 01:38:07 diagonal: 4
[5 6 2 2]
[4 6 7 8]
[4 6 5 7]
[3 2 4 8]

对于反对角线，需要使用len(board) - i，即

for i, row := range board {
    for j := range row {
        board[i][j] = rand.Intn(9)
        if len(board)-i == j {
            log.Println("diagonal:", board[i][j])
        }
    }
}

打印

2021/12/21 01:57:30 diagonal: 8
2021/12/21 01:57:30 diagonal: 5
2021/12/21 01:57:30 diagonal: 2
[5 6 2 2]
[4 6 7 8]
[4 6 5 7]
[3 2 4 8]