Question

How to sort each column of a matrix with strings in C++

Answer 1

#include <iostream>
#include <vector>
#include <algorithm>

void sortColumns(std::vector<std::vector<std::string>>& matrix) {
    int rows = matrix.size();
    int cols = matrix[0].size();

    for (int col = 0; col < cols; col++) {
        // Extract column into a vector
        std::vector<std::string> column;
        for (int row = 0; row < rows; row++) {
            column.push_back(matrix[row][col]);
        }

        // Sort the column
        std::sort(column.begin(), column.end());

        // Place sorted values back into the matrix
        for (int row = 0; row < rows; row++) {
            matrix[row][col] = column[row];
        }
    }
}

void printMatrix(const std::vector<std::vector<std::string>>& matrix) {
    for (const auto& row : matrix) {
        for (const auto& elem : row) {
            std::cout << elem << " ";
        }
        std::cout << "\n";
    }
}

int main() {
    std::vector<std::vector<std::string>> matrix = {
        {"ccc", "zzzz", "x"},
        {"eee", "aaa", "ffff"},
        {"bbb", "gg", "yyyyyy"}
    };

    std::cout << "Original Matrix:\n";
    printMatrix(matrix);

    sortColumns(matrix);

    std::cout << "\nSorted Matrix:\n";
    printMatrix(matrix);
}



/*
run:

Original Matrix:
ccc zzzz x 
eee aaa ffff 
bbb gg yyyyyy 

Sorted Matrix:
bbb aaa ffff 
ccc gg x 
eee zzzz yyyyyy 

*/

 

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Answer 2

#include <iostream>
#include <vector>
#include <algorithm>

void sortColumns(std::vector<std::vector<std::string>>& matrix) {
    int rows = matrix.size();
    int cols = matrix[0].size();

    for (int col = 0; col < cols; col++) {
        // Extract column into a vector
        std::vector<std::string> column;
        for (int row = 0; row < rows; row++) {
            column.push_back(matrix[row][col]);
        }

        // Sort the column
        std::sort(column.begin(), column.end());

        // Place sorted values back into the matrix
        for (int row = 0; row < rows; row++) {
            matrix[row][col] = column[row];
        }
    }
}

void printMatrix(const std::vector<std::vector<std::string>>& matrix) {
    for (const auto& row : matrix) {
        for (const auto& elem : row) {
            std::cout << elem << " ";
        }
        std::cout << "\n";
    }
}

int main() {
    std::vector<std::vector<std::string>> matrix = {
        {"ccc", "zzzz", "x"},
        {"eeee", "aaa", "ffff"},
        {"uu", "hhh", "uuu"},
        {"bbb", "gg", "yyyyyy"}
    };

    std::cout << "Original Matrix:\n";
    printMatrix(matrix);

    sortColumns(matrix);

    std::cout << "\nSorted Matrix:\n";
    printMatrix(matrix);
}



/*
run:

Original Matrix:
ccc zzzz x 
eeee aaa ffff 
uu hhh uuu 
bbb gg yyyyyy 

Sorted Matrix:
bbb aaa ffff 
ccc gg uuu 
eeee hhh x 
uu zzzz yyyyyy 

*/

 

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