Matrix Layer Rotation

//https://www.hackerrank.com/challenges/matrix-rotation-algo/problem/

#include <iostream>

using namespace std;

int main() 
{
	int M, N, R,tmp;
	cin>>M>>N>>R;
	int mat[M][N],i,j;
	for(i = 0; i < M; i++) 
		for(j = 0; j < N; j++) 
			cin>>mat[i][j];
    //calculate no of rings
	int Rings = min(M,N)/2;
	for(i = 0; i < Rings; i++) 
    {
        //calculate num of rotations , without complete rotations
        
		int Rotations = R%(2*(M + N - 4*i) - 4);
        
        //as we go inside each ring, 4 corners r removed so subtract 4i
        //total elements in ring is 2(M + N- 4*i) , but we subtract 4 again as 
        // we dont consider corners while rotating. so it can be written as
        // 2 * ( (M-1) + (N-1) - 4*i ) =  2 * (M + N - 4*i) - 4
        
		for(int rot = 0; rot < Rotations; rot++) 
        {
            // we swap the first element in a clock wise manner, but due 
            // to that the elements move to left i.e, anti-clock wise way
            
            //rotating top row
			for(int j = i; j < N-i-1; j++) 
            {
				tmp = mat[i][j];
				mat[i][j] = mat[i][j+1];
				mat[i][j+1] = tmp;
			}
			// rotating right column
			for(j = i; j < M-i-1; j++) 
            {
				tmp = mat[j][N-i-1];
				mat[j][N-i-1] = mat[j+1][N-i-1];
				mat[j+1][N-i-1] = tmp;
			}
			// rotating bottom row
			for(j = N-i-1; j > i; j--) 
            {
				tmp = mat[M-i-1][j];
				mat[M-i-1][j] = mat[M-i-1][j-1];
				mat[M-i-1][j-1] = tmp;
			}
			// rotating left column
			for(j = M-i-1; j > i+1; j--) 
            {
				tmp = mat[j][i];
				mat[j][i] = mat[j-1][i];
				mat[j-1][i] = tmp;
			}
		}
	}
    //output the matrix
	for(i = 0; i < M; i++)
    {
		for(j = 0; j < N; j++)
			cout<<mat[i][j]<<" ";
		cout<<"\n";
	}
    return 0;
}