Lecture 53 :- Spiral Print A Matrix

Spiral printing a matrix means printing the elements in a spiral pattern, starting from the top-left corner and moving in a clockwise direction.

To achieve this, we use four variables to keep track of the current boundaries of the spiral:

1. top: The topmost row index.
2. bottom: The bottommost row index.
3. left: The leftmost column index.
4. right: The rightmost column index.

We start by printing the elements in the top row from left to right. Then, we increment top to move down to the next row and print the elements in the rightmost column from top to bottom. Next, we decrement right to move to the left column and print the elements in the bottom row from right to left. Finally, we increment left to move to the right column and print the elements in the leftmost column from bottom to top. We repeat these steps until we have printed all the elements in the matrix.

Here's the C++ code to perform spiral printing on a given matrix:

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#include <iostream> #include <vector> void spiralPrintMatrix(std::vector<std::vector<int>>& matrix) {    int rows = matrix.size();    int cols = matrix[0].size();    int top = 0;    int bottom = rows - 1;    int left = 0;    int right = cols - 1;    while (top <= bottom && left <= right) {        // Print top row        for (int i = left; i <= right; i++) {            std::cout << matrix[top][i] << " ";        }        top++;        // Print rightmost column        for (int i = top; i <= bottom; i++) {            std::cout << matrix[i][right] << " ";        }        right--;        // Print bottom row (if applicable)        if (top <= bottom) {            for (int i = right; i >= left; i--) {                std::cout << matrix[bottom][i] << " ";            }            bottom--;        }        // Print leftmost column (if applicable)        if (left <= right) {            for (int i = bottom; i >= top; i--) {                std::cout << matrix[i][left] << " ";            }            left++;        }    } } int main() {    std::vector<std::vector<int>> matrix = {        {1, 2, 3, 4},        {5, 6, 7, 8},        {9, 10, 11, 12},        {13, 14, 15, 16}    };    spiralPrintMatrix(matrix);    return 0; }

Example Output:

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1 2 3 4 8 12 16 15 14 13 9 5 6 7 11 10

In this code, the spiralPrintMatrix function performs the spiral printing on the given matrix. The time complexity of this approach is O(rows * cols), where rows and cols are the dimensions of the matrix.