【LeetCode】566. Reshape the Matrix

Python版本：python3.6.2

566. Reshape the Matrix

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

自己的代码：

class Solution:
    def matrixReshape(self, nums, r, c):
        """
        :type nums: List[List[int]]
        :type r: int
        :type c: int
        :rtype: List[List[int]]
        """
        tmp = []
        res = [[]for i in range(r)]
        count = 0
        if len(nums) * len(nums[0]) == r * c:
            for i in range(len(nums)):
                for j in range(len(nums[0])):
                    tmp.append(nums[i][j])
            for x in range(r):
                y = 0
                while y < c:
                    res[x].append(tmp[count])
                    count += 1
                    y += 1
            return res
        else:
            return nums

检验下：

nums = [[1, 2], [3, 4]]
a = Solution()
print(a.matrixReshape(nums=nums, r=2, c=4))

输出：

"D:\Program files\python3.6.2\python.exe" "D:/sunfl/sunflower/study/LeetCode/566. Reshape the Matrix/566. Reshape the Matrix.py"
[[1, 2], [3, 4]]

进程已结束,退出代码0

速度有点出乎意料，因为是在外面书店写的，有点吵

大神给出了3种解法，列出其中最清晰易懂的一个:

#Solution 1 - NumPy
class Solution:
    def matrixReshape(self, nums, r, c):
        """
        :type nums: List[List[int]]
        :type r: int
        :type c: int
        :rtype: List[List[int]]
        """
        def matrixReshape(self, nums, r, c):
            try:
                return np.reshape(nums, (r, c)).tolist()
            except:
                return nums

一开始我也想到了用numpy，但是一想这么简单不可能，emm.....实事告诉我们，不要怀疑，不要困惑，有工具就用现成的工具，不要重复造轮子。