Create 2D array¶

Declare¶

dataType[][] arr
int[][] arr

Instantiate¶

ArrayRefVar = new datatype[row][col]
arr = new int[2][3]

Initialize¶

a[0][0] = 10;
a[0][1] = 20;
a[0][2] = 30;
a[1][0] = 40;
a[1][1] = 50;
a[1][2] = 60;

Declaration, instantiation and initialization¶

int[][] arr = {{10,20,30},{40,50,60}}

Time complexity¶

int[][] arr ------------------------------ O(1)
arr = new int[2][3] ---------------------- O(1)
a[0][0] = 10; --------------------------|
a[0][1] = 20; --------------------------|
a[0][2] = 30; --------------------------|- O(mn)
a[1][0] = 40; --------------------------|
a[1][1] = 50; --------------------------|
a[1][2] = 60; --------------------------|

int[][] arr = {{10,20,30},{40,50,60}} ---- O(1)