Create Rotate a matrix by 90 degree without using any extra space

Rotate a matrix by 90 degree without using any extra space

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+// C++ program for left
+// rotation of matrix by 90 degree
+// without using extra space
+#include <bits/stdc++.h>
+using namespace std;
+#define R 4
+#define C 4
+
+// After transpose we swap
+// elements of column
+// one by one for finding left
+// rotation of matrix
+// by 90 degree
+void reverseColumns(int arr[R][C])
+{
+	for (int i = 0; i < C; i++)
+		for (int j = 0, k = C - 1; j < k; j++, k--)
+			swap(arr[j][i], arr[k][i]);
+}
+
+// Function for do transpose of matrix
+void transpose(int arr[R][C])
+{
+	for (int i = 0; i < R; i++)
+		for (int j = i; j < C; j++)
+			swap(arr[i][j], arr[j][i]);
+}
+
+// Function for print matrix
+void printMatrix(int arr[R][C])
+{
+	for (int i = 0; i < R; i++) {
+		for (int j = 0; j < C; j++)
+			cout << arr[i][j] << " ";
+		cout << '\n';
+	}
+}
+
+// Function to anticlockwise
+// rotate matrix by 90 degree
+void rotate90(int arr[R][C])
+{
+	transpose(arr);
+	reverseColumns(arr);
+}
+
+// Driven code
+int main()
+{
+	int arr[R][C] = { { 1, 2, 3, 4 },
+					{ 5, 6, 7, 8 },
+					{ 9, 10, 11, 12 },
+					{ 13, 14, 15, 16 } };
+	rotate90(arr);
+	printMatrix(arr);
+	return 0;
+}