用golang寫這道題的做法完全不同，用到了gorutine， channel，寫著挺有意思的

題目

In MATLAB, there is a very useful function called 'reshape', which can reshape a matrix into a new one with different size but keep its original data.

You're given a matrix represented by a two-dimensional array, and two positive integers r and c representing the row number and column number of the wanted reshaped matrix, respectively.

The reshaped matrix need to be filled with all the elements of the original matrix in the same row-traversing order as they were.

If the 'reshape' operation with given parameters is possible and legal, output the new reshaped matrix; Otherwise, output the original matrix.

Example 1:

Input:
nums =
[[1,2],
[3,4]]
r = 1, c = 4
Output:
[[1,2,3,4]]
Explanation:
The row-traversing of nums is [1,2,3,4]. The new reshaped matrix is a 1 * 4 matrix, fill it row by row by using the previous list.

Example 2:

Input:
nums =
[[1,2],
[3,4]]
r = 2, c = 4
Output:
[[1,2],
[3,4]]

Explanation:
There is no way to reshape a 2 * 2 matrix to a 2 * 4 matrix. So output the original matrix.
Note:

1. The height and width of the given matrix is in range [1, 100].
2. The given r and c are all positive.

題目大意：

給定二維矩陣nums，將其轉化為r行c列的新矩陣。若無法完成轉化，返回原矩陣。

注意：

給定矩陣的高度和寬度范圍[1, 100]
r和c都是正數

解題思路

1. origin_r * origin_c 的矩陣 reshape為 rc的矩陣，需要滿足：
   origin_r * origin_c=rc
2. 元素位置對應的關系
   如果將矩陣橫向展開為一維數組，元素個數為n=origin_r * origin_c
   在元素在一維數組中對應的位置i：
   原矩陣位置[i/origin_c,i%origin_c]
   新矩陣位置[i/c,i%c]

代碼

reshapeMatrix.go

package _566_Reshape_Matrix

import "fmt"

func MatrixReshape(nums [][]int, r int, c int) [][]int {
    var chanInt chan int
    chanInt = make(chan int)

    var length int
    go func(len *int) {
        for _, v1 := range nums {
            for _, v := range v1 {
                (*len)++
                fmt.Printf("len1:%+v\n", length)
                chanInt <- v
            }
        }

        for {
            chanInt <- 0
        }
    }(&length)


    var ret [][]int
    for i := 0; i < r; i++ {
        var lineRet []int
        for j := 0; j < c; j++ {
            v := <- chanInt

            lineRet = append(lineRet, v)
        }
        ret = append(ret, lineRet)
    }

    fmt.Printf("len2:%+v\n", length)
    fmt.Printf("ret:%+v\n", ret)
    if r * c != length {
        return nums
    }

    return ret
}

測試

reshapeMatrix_test.go

package _566_Reshape_Matrix

import "testing"

func TestMatrixReshape(t *testing.T) {
    input := [][]int{
        {1, 2},
        {3, 4},
    }
    ret := MatrixReshape(input, 1, 4)

    t.Logf("%+v", ret)
}