Matrix Operations

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import java.util.ArrayList;
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import java.util.List;
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public void fn(List<List<Integer>> matrix) {
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    List<List<Integer>> createMatrix = new ArrayList<>();
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    List<List<Integer>> copyMatrix = new ArrayList<>();
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    int r = matrix.size();
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    int c = matrix.get(0).size();
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    for (int i = 0; i < r; i++) {
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        List<Integer> row = new ArrayList<>();
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        for (int j = 0; j < c; j++) {
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            row.add(0);
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        }
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        createMatrix.add(row);
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    }
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    for (List<Integer> row : matrix) {
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        copyMatrix.add(new ArrayList<>(row));
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    }
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}

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import java.util.ArrayList;
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import java.util.List;
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public void fn(List<List<Integer>> matrix) {
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    List<Integer> mainDiagonal = new ArrayList<>();
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    List<Integer> antiDiagonal = new ArrayList<>();
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    int r = matrix.size();
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    int c = matrix.get(0).size();
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    for (int i = 0; i < Math.min(r, c); i++) {
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        mainDiagonal.add(matrix.get(i).get(i));
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    }
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    for (int i = 0; i < Math.min(r, c); i++) {
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        antiDiagonal.add(matrix.get(i).get(c - 1 - i));
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    }
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}

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import java.util.ArrayList;
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import java.util.List;
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public static void fn(List<List<Integer>> matrix) {
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    List<List<Integer>> transpose = new ArrayList<>();
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    List<List<Integer>> rotateLeft = new ArrayList<>();
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    List<List<Integer>> rotateRight = new ArrayList<>();
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    int r = matrix.size();
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    int c = matrix.get(0).size();
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    for (int j = 0; j < c; j++) {
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        List<Integer> newRow = new ArrayList<>();
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        for (int i = 0; i < r; i++) {
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            newRow.add(matrix.get(i).get(j));
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        }
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        transpose.add(newRow);
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    }
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    for (int i = transpose.size() - 1; i >= 0; i--) {
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        rotateLeft.add(transpose.get(i));
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    }
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    for (List<Integer> row : transpose) {
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        List<Integer> newRow = new ArrayList<>();
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        for (int i = row.size() - 1; i >= 0; i--) {
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            newRow.add(row.get(i));
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        }
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        rotateRight.add(newRow);
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    }
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}