创建二维数组

python

浅拷贝

dp = [[0] * 3 ]*3
dp[1][1] = 1
print(dp)
#[[0, 1, 0], [0, 1, 0], [0, 1, 0]]

列表推导式

dp = [[0] * 3 for j in range(3)]
dp[1][1] = 1
print(dp)
#[[0, 0, 0], [0, 1, 0], [0, 0, 0]]

dp = [[0 for i in range(3)] for j in range(3)]  #里边那层是列，外边那层才是行
dp[1][1] = 1
print(dp)
#[[0, 0, 0], [0, 1, 0], [0, 0, 0]]

numpy

• numpy创建零数组

  import numpy as np
  dp = np.zeros((3,3),dtype = int)
  dp[1][1] = 1
  print(dp)
  #[[0 0 0]
  # [0 1 0]
  # [0 0 0]]
  

• numpy创建递增数组

  import numpy as np
  dp = np.arange(12).reshape(4, 3)
  print(dp)
  #[[ 0  1  2]
  # [ 3  4  5]
  # [ 6  7  8]
  # [ 9 10 11]]
  

• numpy创建空数组

  import numpy as np
  dp = np.empty((3,3),dtype = int)
  print(dp)
  #[[         1          0          8]  元素随机
  # [         0          8          0]
  # [         8          0 1852796001]]
  

c++

Normal

	int** arr = new int* [row];
	for (int i = 0; i < row; ++i)
		arr[i] = new int[col];

注意自己回收内存

	for (int i = 0; i < row; ++i)
		delete[]arr[i];
	delete[]arr;

Vector

	vector<vector<int>> arr(row,vector<int>(col,init_value));