How to convert a 2-d array of size (m x n) into 1-d array and how to store the element at position [i, j] of 2-d array in 1-d array? Clearly, the size of 1-d array is the number of elements in 2-d array i.e. (m x n). If the elements in the 2-d array are stored in row-major order. Then, the element at index [i, j] in 2-d array will be stored in 1-d array at index k as:
k = j + (i * total_no_of_columns_in_matrix)
If the elements in the 2-d array are stored in column-major order, the value of index k will be
k = i + (j * total_no_of_rows_in_matrix)
For more details about Row-major and Column-major order, refer to: https://en.wikipedia.org/wiki/Row-major_order
Examples :
Given 2-d array:
// array is formed in row-major order
__________________________
| |
|1(0,0) 2(0,1) 3(0,2)|
| |
|4(1,0) 5(1,1) 6(1,2)|
|__________________________|
// The elements in parenthesis represents the
// index of the particular element in 2-d array.
Index of element at (0,1) in 1-d array will be:
k(0,1) = 1 + 0 * 3 = 1
Index of element at (1,1) in 1-d array will be:
k(1,1) = 1 + 1 * 3 = 4
C++
// C++ program to emulate 2-d array using // 1-d array #include<stdio.h> #define n 3 #define m 3 #define max_size 100 int main() { // Intialising a 2-d array int grid[n][m] = {{1, 2, 3}, {4, 5, 6}, {7, 8, 9}}; // storing elements in 1-d array int i, j, k = 0; int array[max_size]; for (i=0; i<n; i++) { for (j=0; j<m; j++) { k = i*m + j; array[k] = grid[i][j]; k++; } } // displaying elements in 1-d array for (i=0; i<n; i++) { for (j=0; j<m; j++) printf("%d ", *(array + i*m + j)); printf("\n"); } return 0; } |
Java
// Java program to emulate 2-d array using // 1-d array class GFG { // Driver program public static void main(String arg[]) { // Declaring number of rows and columns int n = 3, m = 3; int array[]=new int[100]; // Intialising a 2-d array int grid[][] = {{1, 2, 3}, {4, 5, 6}, {7, 8, 9}}; // storing elements in 1-d array int i, j, k = 0; for (i = 0; i < n; i++) { for (j = 0; j < m; j++) { k = i * m + j; array[k] = grid[i][j]; k++; } } // displaying elements in 1-d array for (i = 0; i < n; i++) { for (j = 0; j < m; j++) System.out.print((array[i * m + j])+" "); System.out.print("\n"); } } } // This code is contributed by Anant Agarwal. |
Python3
# Python program to emulate 2-d # array using 1-d array # Declaring number of rows and columns n = 3; m = 3 array = [0 for i in range(100)] # Intialising a 2-d array grid = [[1, 2, 3], [4, 5, 6], [7, 8, 9]]; # storing elements in 1-d array k = 0 for i in range(n): for j in range(m): k = i*m + j array[k] = grid[i][j] k += 1 # displaying elements in 1-d array for i in range(n): for j in range(m): print((array[i*m + j]), " ", end = "") print() # This code is contributed by Anant Agarwal. |
C#
// C# program to emulate 2-d array using // 1-d array using System; class GFG { // Driver program public static void Main() { // Declaring number of rows and columns int n = 3, m = 3; int []array=new int[100]; // Intialising a 2-d array int [,]grid = {{1, 2, 3}, {4, 5, 6}, {7, 8, 9}}; // storing elements in 1-d array int i, j, k = 0; for (i = 0; i < n; i++) { for (j = 0; j < m; j++) { k = i * m + j; array[k] = grid[i, j]; k++; } } // displaying elements in 1-d array for (i = 0; i < n; i++) { for (j = 0; j < m; j++) Console.Write((array[i * m + j])+" "); Console.Write("\n"); } } } // This code is contributed by nitin mittal |
Output:
1 2 3 4 5 6 7 8 9
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