Merge pull request #202 from AnirudhPhophalia/sparsematrix_cpp_anirudhphophalia

Add sparse matrix operations implementation and documentation

Author: Pradeepsingh61

CPP/data_structures/example.cpp

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+#include <iostream>
+#include <vector>
+using namespace std;
+
+// Simplified version for demonstration
+struct Element {
+    int row, col, value;
+    Element(int r, int c, int v) : row(r), col(c), value(v) {}
+};
+
+class SparseMatrix {
+private:
+    vector<Element> elements;
+    int rows, cols;
+
+public:
+    SparseMatrix(int r, int c) : rows(r), cols(c) {}
+    
+    void addElement(int row, int col, int value) {
+        if (value != 0) {
+            elements.push_back(Element(row, col, value));
+        }
+    }
+    
+    void display() const {
+        cout << "Sparse Matrix (" << rows << "x" << cols << "):\n";
+        cout << "Row\tCol\tValue\n";
+        for (const auto& elem : elements) {
+            cout << elem.row << "\t" << elem.col << "\t" << elem.value << endl;
+        }
+        cout << endl;
+    }
+    
+    void displayFull() const {
+        cout << "Full Matrix:\n";
+        for (int i = 0; i < rows; i++) {
+            for (int j = 0; j < cols; j++) {
+                int value = 0;
+                for (const auto& elem : elements) {
+                    if (elem.row == i && elem.col == j) {
+                        value = elem.value;
+                        break;
+                    }
+                }
+                cout << value << " ";
+            }
+            cout << endl;
+        }
+        cout << endl;
+    }
+};
+
+int main() {
+    cout << "=== SPARSE MATRIX EXAMPLE ===\n\n";
+    
+    // Create first matrix: 3x3
+    // 1  0  2
+    // 0  0  0  
+    // 3  0  4
+    SparseMatrix matrix1(3, 3);
+    matrix1.addElement(0, 0, 1);
+    matrix1.addElement(0, 2, 2);
+    matrix1.addElement(2, 0, 3);
+    matrix1.addElement(2, 2, 4);
+    
+    cout << "Matrix 1:\n";
+    matrix1.display();
+    matrix1.displayFull();
+    
+    // Create second matrix: 3x3
+    // 0  5  0
+    // 6  0  7
+    // 0  8  0
+    SparseMatrix matrix2(3, 3);
+    matrix2.addElement(0, 1, 5);
+    matrix2.addElement(1, 0, 6);
+    matrix2.addElement(1, 2, 7);
+    matrix2.addElement(2, 1, 8);
+    
+    cout << "Matrix 2:\n";
+    matrix2.display();
+    matrix2.displayFull();
+    
+    cout << "For complete operations (addition, multiplication, etc.),\n";
+    cout << "please run the main program: sparse_matrix_operations.cpp\n";
+    
+    return 0;
+}

CPP/data_structures/sparse_matrix_README.md

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+# Sparse Matrix Operations in C++
+
+This program implements various operations on sparse matrices using C++. A sparse matrix is a matrix that contains mostly zero elements, making it memory-efficient to store only the non-zero elements.
+
+## Features
+
+- **Addition**: Add two sparse matrices of the same dimensions
+- **Subtraction**: Subtract one sparse matrix from another
+- **Multiplication**: Matrix multiplication following standard rules
+- **Element-wise Division**: Divide corresponding elements (not standard matrix division)
+- **Transpose**: Get the transpose of a sparse matrix
+
+## Data Structure
+
+The program uses a triplet representation where each non-zero element is stored as:
+- Row index
+- Column index  
+- Value
+
+## How to Compile and Run
+
+```bash
+g++ -o sparse_matrix_operations sparse_matrix_operations.cpp
+./sparse_matrix_operations
+```
+
+## Usage Examples
+
+### Example 1: Matrix Addition
+```
+Matrix A (3x3):
+1  0  2
+0  0  0
+3  0  4
+
+Matrix B (3x3):  
+0  5  0
+6  0  7
+0  8  0
+
+Result A + B:
+1  5  2
+6  0  7
+3  8  4
+```
+
+### Example 2: Matrix Multiplication
+```
+Matrix A (2x3):
+1  0  2
+0  3  0
+
+Matrix B (3x2):
+4  0
+0  5
+6  0
+
+Result A × B:
+16  0
+0  15
+```
+
+### Input Format
+
+When prompted, enter:
+1. Number of rows
+2. Number of columns  
+3. Number of non-zero elements
+4. For each non-zero element: row_index column_index value
+
+**Note**: Indices are 0-based (start from 0)
+
+### Example Input Session
+```
+Enter number of rows: 3
+Enter number of columns: 3
+Enter number of non-zero elements: 4
+Element 1: 0 0 1
+Element 2: 0 2 2  
+Element 3: 2 0 3
+Element 4: 2 2 4
+```
+
+## Operations Details
+
+### Addition and Subtraction
+- Matrices must have the same dimensions
+- Corresponding elements are added/subtracted
+- Result maintains sparse representation
+
+### Multiplication  
+- First matrix columns must equal second matrix rows
+- Standard matrix multiplication algorithm
+- Efficiently handles sparse matrices
+
+### Element-wise Division
+- Matrices must have same dimensions
+- Divides corresponding non-zero elements
+- Warns about division by zero
+
+### Transpose
+- Swaps rows and columns
+- Dimensions change from m×n to n×m
+
+## Memory Efficiency
+
+The sparse matrix representation is memory efficient:
+- Only stores non-zero elements
+- Space complexity: O(number of non-zero elements)
+- Ideal for matrices with many zeros
+
+## Time Complexity
+
+- **Addition/Subtraction**: O(m + n) where m, n are non-zero elements in each matrix
+- **Multiplication**: O(m × n) where m, n are non-zero elements in each matrix  
+- **Transpose**: O(k) where k is number of non-zero elements
+
+## Error Handling
+
+The program includes error handling for:
+- Invalid matrix dimensions for operations
+- Division by zero
+- Invalid array indices
+- Memory allocation issues
+
+## Limitations
+
+- Element-wise division is not standard matrix division
+- Integer arithmetic only (can be extended to floating-point)
+- No matrix inversion or other advanced operations
+
+## Future Enhancements
+
+Possible improvements:
+- Support for floating-point numbers
+- Matrix determinant calculation
+- Matrix inversion for invertible matrices
+- File I/O for large matrices
+- Optimized algorithms for very large sparse matrices