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    <p>I had a go. It's a bit naive as I didn't know the algorithm for it. It works for any matrix whose size is an odd number.</p> <p>[EDIT: now with comments]</p> <pre><code>#include &lt;iostream&gt; #include &lt;cstdlib&gt; #include &lt;cassert&gt; using namespace std; void printMatrix(int** mat, int s) { for (int i = 0; i &lt; s; ++i) { for (int j = 0; j &lt; s; ++j) { cout &lt;&lt; mat[i][j] &lt;&lt; " "; } cout &lt;&lt; "\n"; } } // For the matrix of size s located at mat1[src_x][src_y], shift the numbers on its // perimeter in a counter-clockwise direction, and store the result in mat2. void periShift(int** mat1, int src_x, int src_y, int s, int** mat2, int shift) { // Bottom edge for (int i = 0; i &lt; s; ++i) { int x = i; int y = 0; // Max x on this edge int X = s - 1; // The amount of space we have to shift x int a = X - x; // Clip the value to shift if (a &gt; shift) a = shift; // If a &lt; shift, the number is to be shifted round the corner (up the right side) by b places. int b = shift - a; mat2[src_x + x + a][src_y + y + b] = mat1[src_x + x][src_y + y]; } // Top edge for (int i = 0; i &lt; s; ++i) { int x = s - 1 - i; int y = s - 1; int a = x; if (a &gt; shift) a = shift; int b = shift - a; mat2[src_x + x - a][src_y + y - b] = mat1[src_x + x][src_y + y]; } // Right edge for (int i = 0; i &lt; s; ++i) { int y = i; int x = s - 1; int Y = s - 1; int a = Y - y; if (a &gt; shift) a = shift; int b = shift - a; mat2[src_x + x - b][src_y + y + a] = mat1[src_x + x][src_y + y]; } // Left edge for (int i = 0; i &lt; s; ++i) { int y = s - 1 - i; int x = 0; int a = y; if (a &gt; shift) a = shift; int b = shift - a; mat2[src_x + x + b][src_y + y - a] = mat1[src_x + x][src_y + y]; } } void rotateMatrix(int** mat1, int** mat2, int s) { // The size of the matrix's perimeter int peri = 4 * (s - 1); assert(peri % 8 == 0); // As 45 degrees is an eighth of a full circle, the numbers on the matrix's perimeter // should end up (peri / 8) places counter-clockwise from where they started. int shift = peri / 8; // Work our way out from the centre of the matrix to the edge, performing the perimeter shift // on each submatrix. I.e. the 3x3 matrix in the middle has its perimeter shifted 1 position // counter-clockwise, the 4x4 matrix has its position shifted 2 places, etc. for (int i = 0; i &lt; s / 2; ++i) { int x = i; int y = i; // Shift the perimeter of the submatrix periShift(mat1, x, y, s - 2 * i, mat2, shift - i); } // Copy the centre value over mat2[s / 2][s / 2] = mat1[s / 2][s / 2]; } int main() { int s = 0; while (1) { cout &lt;&lt; "Enter matrix size:\n"; cin &gt;&gt; s; if (s % 2 == 1) break; cout &lt;&lt; "Invalid matrix size. Must be an odd number.\n"; } // Construct 2 matrices int** mat1 = new int*[s]; for (int i = 0; i &lt; s; ++i) mat1[i] = new int[s]; int** mat2 = new int*[s]; for (int i = 0; i &lt; s; ++i) mat2[i] = new int[s]; // Fill first matrix with random numbers (0 .. 9) srand(time(NULL)); for (int i = 0; i &lt; s; ++i) { for (int j = 0; j &lt; s; ++j) { mat1[i][j] = rand() % 10; } } cout &lt;&lt; "Matrix =\n"; printMatrix(mat1, s); rotateMatrix(mat1, mat2, s); cout &lt;&lt; "\nRotated matrix =\n"; printMatrix(mat2, s); // Delete matrices for (int i = 0; i &lt; s; ++i) delete[] mat1[i]; delete mat1; for (int i = 0; i &lt; s; ++i) delete[] mat2[i]; delete mat2; return EXIT_SUCCESS; } </code></pre> <p>EDIT: In theory, the whole perimeter shift thing is unnecessary if you can figure out the mathematical function that maps the position of values in matrix A to their new position in matrix B.</p>
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    1. COit works fine...but if u can add some comments so i could understand what is happening exactly that would be great.
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