#include <stdio.h>

// Define a struct to represent a sparse matrix element
struct SparseElement
{
        int row;
        int col;
        int value;
};

// Function to perform fast transpose on a sparse matrix
void fastTranspose(struct SparseElement A[], struct SparseElement B[], int numRows, int numCols) 
{
        int numTerms = A[0].value; // Number of non-zero elements
        int total[numCols], index[numCols];

        // Initialize arrays
        for (int i = 0; i < numCols; i++) 
        {
                total[i] = 0;
                index[i] = 0;
        }

        // Calculate the number of non-zero elements in each column
        for (int i = 1; i <= numTerms; i++) 
        {
                total[A[i].col]++;
        }

        // Calculate the starting position of each column in the B matrix
        index[0] = 1;
        for (int i = 1; i < numCols; i++) 
        {
                index[i] = index[i - 1] + total[i - 1];
        }

        //Initialize the meta data of B 
        B[0].row = A[0].col;
        B[0].col = A[0].row;
        B[0].value = A[0].value;

        // Perform the transpose
        for (int i = 1; i <= numTerms; i++) 
        {
                int j = index[A[i].col]++;
                B[j].row = A[i].col;
                B[j].col = A[i].row;
                B[j].value = A[i].value;
        }

        // Set the number of non-zero elements in the B matrix
        // B[0].value = numTerms;
}

int main() {
        int numRows, numCols, numNonZero;

        // Input dimensions and non-zero elements
        printf("Enter the number of rows: ");
        scanf("%d", & numRows);
        printf("Enter the number of columns: ");
        scanf("%d", & numCols);
        printf("Enter the number of non-zero elements: ");
        scanf("%d", & numNonZero);

        // Create arrays for the A and B matrices
        struct SparseElement A[numNonZero + 1]; // +1 for metadata
        struct SparseElement B[numNonZero + 1]; // +1 for metadata

        // Input non-zero elements
        printf("Enter non-zero elements (row col value):\n");
        for (int i = 1; i <= numNonZero; i++) 
        {
                scanf("%d %d %d", & A[i].row, & A[i].col, & A[i].value);
        }

        // Set metadata for both matrices
        A[0].row = numRows;
        A[0].col = numCols;
        A[0].value = numNonZero;

        // Perform fast transpose
        fastTranspose(A, B, numRows, numCols);

        // Display the A and B matrices
        printf("\nA Sparse Matrix:\n");
        for (int i = 0; i <= numNonZero; i++)
        {
                printf("%d %d %d\n", A[i].row, A[i].col, A[i].value);
        }

        printf("\nB Sparse Matrix:\n");
        for (int i = 0; i <= numNonZero; i++) 
        {
                printf("%d %d %d\n", B[i].row, B[i].col, B[i].value);
        }

        return 0;
}

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About C

C language is one of the most popular general-purpose programming language developed by Dennis Ritchie at Bell laboratories for UNIX operating system. The initial release of C Language was in the year 1972. Most of the desktop operating systems are written in C Language.

Key features:

  • Structured Programming
  • Popular system programming language
  • UNIX, MySQL and Oracle are completely written in C.
  • Supports variety of platforms
  • Efficient and also handle low-level activities.
  • As fast as assembly language and hence used as system development language.

Syntax help

Loops

1. If-Else:

When ever you want to perform a set of operations based on a condition if-else is used.

if(conditional-expression) {
   // code
} else {
   // code
}

You can also use if-else for nested Ifs and if-else-if ladder when multiple conditions are to be performed on a single variable.

2. Switch:

Switch is an alternative to if-else-if ladder.

switch(conditional-expression) {    
case value1:    
 // code    
 break;  // optional  
case value2:    
 // code    
 break;  // optional  
...    
    
default:     
 // code to be executed when all the above cases are not matched;    
}

3. For:

For loop is used to iterate a set of statements based on a condition.

for(Initialization; Condition; Increment/decrement){  
  // code  
}

4. While:

While is also used to iterate a set of statements based on a condition. Usually while is preferred when number of iterations are not known in advance.

while(condition) {  
 // code 
}

5. Do-While:

Do-while is also used to iterate a set of statements based on a condition. It is mostly used when you need to execute the statements atleast once.

do {
  // code 
} while (condition);

Arrays

Array is a collection of similar data which is stored in continuous memory addresses. Array values can be fetched using index. Index starts from 0 to size-1.

Syntax

One dimentional Array:

data-type array-name[size];

Two dimensional array:

data-type array-name[size][size];

Functions

Function is a sub-routine which contains set of statements. Usually functions are written when multiple calls are required to same set of statements which increases re-usuability and modularity.

Two types of functions are present in C

  1. Library Functions:

Library functions are the in-built functions which are declared in header files like printf(),scanf(),puts(),gets() etc.,

  1. User defined functions:

User defined functions are the ones which are written by the programmer based on the requirement.

How to declare a Function

return_type function_name(parameters);

How to call a Function

function_name (parameters)

How to define a Function

return_type function_name(parameters) {  
  //code
}