题目

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.

题目大意：

给定二维矩阵nums，将其转化为r行c列的新矩阵。若无法完成转化，返回原矩阵。

注意：

给定矩阵的高度和宽度范围[1, 100]
r和c都是正数

解题思路

1. origin_r * origin_c 的矩阵 reshape为 rc的矩阵，需要满足：
   origin_r * origin_c=rc
2. 元素位置对应的关系
   如果将矩阵横向展开为一维数组，元素个数为n=origin_r * origin_c
   在元素在一维数组中对应的位置i：
   原矩阵位置[i/origin_c,i%origin_c]
   新矩阵位置[i/c,i%c]

代码

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
}

测试

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)
}

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