ADVANCED DATA STRUCTURES PROGRAM • LEVEL 10 — SPARSE MATRICES

Reconstruct a Dense Matrix from Triplets

Learn how to reconstruct a dense matrix from triplets using a clear C program.

IntermediateSparse representationTriplet form

PROBLEM UNDERSTANDING

Input and expected output

Sample input

No input required

Sample output

0 5 0
2 0 7

COMPLETE C PROGRAM

Complete C implementation

#include <stdio.h>

int main(void)
{
    int triplets[][3] = {{0, 1, 5}, {1, 0, 2}, {1, 2, 7}};
    int matrix[2][3] = {{0}};
    for (int index = 0; index < 3; index++) matrix[triplets[index][0]][triplets[index][1]] = triplets[index][2];
    for (int row = 0; row < 2; row++)
        for (int column = 0; column < 3; column++) printf("%d%c", matrix[row][column], column == 2 ? '\n' : ' ');
    return 0;
}

CURRENT STEP

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SELECTED LINE

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EXPECTED OUTPUT FOR THE SAMPLE

0 5 0
2 0 7

0%Step 0 of 0

PROGRAM EXPLANATION

Algorithm and explanation

Read the required input values.
Initialize zeros and place every triplet value at its stored coordinates.
Display the computed result.

Initialize zeros and place every triplet value at its stored coordinates.

EFFICIENCY

Time and space complexity

Time complexity

O(rows * columns + non-zero)

Auxiliary space

O(non-zero elements)

DEBUGGING CHECKLIST

Common mistakes

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Use the correct format specifier for every variable.

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Initialize variables before using their values.

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Check braces, semicolons and input order carefully.

Try it yourself

Practice: Run the program with the sample input, predict its output, and then test one boundary case of your own.