C++ program to Convert a Matrix to Sparse Matrix

Given a matrix with most of its elements as 0, convert this matrix to sparse matrix in C++

Examples:

Input: Matrix:
0 1 0 0 
0 0 2 0 
0 3 0 0 
0 0 5 0 
0 0 0 4 
Output: Sparse Matrix: 
0 1 1
1 2 2
2 1 3
3 2 5
4 3 4
Explanation:
Here the Sparse matrix is represented
in the form Row Column Value

Hence the row 0 1 1 means that the value
of the matrix at row 0 and column 1 is 1

Recommended: Please try your approach on {IDE} first, before moving on to the solution.

Approach:

Get the matrix with most of its elements as 0.
Create a new 2D array to store the Sparse Matrix of only 3 columns (Row, Column, Value).
Iterate through the Matrix, and check if an element is non zero. In this case insert this element into the Sparse Matrix.
After each insertion, increment the value of variable length(here ‘len’). This will serve as the row dimension of the Sparse Matrix
Print the Dimension of the Sparse Matrix and its elements.

// C++ program to convert a Matrix 
// into Sparse Matrix 
  
#include <iostream> 
using namespace std; 
  
// Maximum number of elements in matrix 
#define MAX 100 
  
// Array representation 
// of sparse matrix 
//[][0] represents row 
//[][1] represents col 
//[][2] represents value 
int data[MAX][3]; 
  
// total number of elements in matrix 
int len; 
  
// insert elements into sparse matrix 
void insert(int r, int c, int val) 
{ 
    // insert row value 
    data[len][0] = r; 
  
    // insert col value 
    data[len][1] = c; 
  
    // insert element's value 
    data[len][2] = val; 
  
    // increment number of data in matrix 
    len++; 
} 
  
// printing Sparse Matrix 
void print() 
{ 
    cout << "\nDimension of Sparse Matrix: "
         << len << " x " << 3; 
    cout << "\nSparse Matrix: \nRow Column Value\n"; 
  
    for (int i = 0; i < len; i++) { 
  
        cout << data[i][0] << " "
             << data[i][1] << " "
             << data[i][2] << "\n"; 
    } 
} 
  
// Driver code 
int main() 
{ 
    int i, j; 
    int r = 5, c = 4; 
  
    // Get the matrix 
    int a[r] = { { 0, 1, 0, 0 }, 
                    { 0, 0, 2, 0 }, 
                    { 0, 3, 0, 0 }, 
                    { 0, 0, 5, 0 }, 
                    { 0, 0, 0, 4 } }; 
  
    // print the matrix 
    cout << "\nMatrix:\n"; 
    for (i = 0; i < r; i++) { 
        for (j = 0; j < c; j++) { 
            cout << a[i][j] << " "; 
        } 
        cout << endl; 
    } 
  
    // iterate through the matrix and 
    // insert every non zero elements 
    // in the Sparse Matrix 
    for (i = 0; i < r; i++) 
        for (j = 0; j < c; j++) 
            if (a[i][j] > 0) 
                insert(i, j, a[i][j]); 
  
    // Print the Sparse Matrix 
    print(); 
  
    return 0; 
} 

Output:

Matrix:
0 1 0 0 
0 0 2 0 
0 3 0 0 
0 0 5 0 
0 0 0 4 

Dimension of Sparse Matrix: 5 x 3
Sparse Matrix: 
Row Column Value
0 1 1
1 2 2
2 1 3
3 2 5
4 3 4

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Recommended: Please try your approach on {IDE} first, before moving on to the solution.

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