Problem
In MATLAB, there is a handy function called reshape which can reshape an m x n matrix into a new one with a different size r x c keeping its original data.
You are given an m x n matrix mat and two integers r and c representing the row number and column number of the wanted reshaped matrix.
The reshaped matrix should 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.
m == mat.length n == mat[i].length 1 <= m, n <= 100 -1000 <= mat[i][j] <= 1000 1 <= r, c <= 300
Thinking
- first check if m _ n == r _ c
- Filling the new matrix
- keep two state variables: i and j. every time j + 1, check if j >= c. If so, clear j and add 1 to i
from typing import List
def matrixReshape(mat: List[List[int]], r: int, c: int) -> List[List[int]]:
m = len(mat)
n = len(mat[0])
if m * n != r * c:
return mat
cur_r = 0
cur_c = 0
new_matrix = [[0 for j in range(c)] for i in range(r)]
for i in range(m):
for j in range(n):
new_matrix[cur_r][cur_c] = mat[i][j]
cur_c += 1
if cur_c >= c:
cur_c = 0
cur_r += 1
return new_matrix
if __name__ == "__main__":
print(matrixReshape([[1, 2], [3, 4]], 1, 4))
