Matrix Rotation - study code - google, like the variable name: int tl_corner, top-left corner, and also 4 comments lines for each for loop.

matrixRotation_google1.cpp

#include <iostream>
using namespace std;
int main() {
	int m,n,r;
	cin >> m >> n >> r;
	int matrix[m][n];
	for (int i = 0; i < m; ++i) {
		for (int j=0; j<n; ++j) {
			cin>>matrix[i][j];
		}
	}
	
	// find how many layers do we need to rotate.
	int layer = n;
	if (m < n) {
		layer = m;
	}

    for (int i =0; i < (layer>>1); ++i){
        int new_n = n-2*i;
        int new_m = m -2*i;
        int rotate = r%(2*new_n+2*new_m-4);
        while(rotate--){
            // rotate top row to the left by 1.
            int tl_corner = matrix[i][i];
            for (int c= i; c < n - 1 - i;++c){
                matrix[i][c] = matrix[i][c+1]; 
            }
            // rotate right column up by 1.
            for (int r=i; r< m- 1- i;++r) {
                matrix[r][n-1-i] = matrix[r+1][n-1-i]; 
            }
            // rotate bottom right by 1.
            for (int c=n-1-i; c>i; --c){
                matrix[m-1-i][c] = matrix[m-1-i][c-1];
            }
            // rotate left column down by 1.
            for (int r=m-1-i; r>i+1; --r) {
                matrix[r][i]=matrix[r-1][i];
            }
            matrix[i+1][i] = tl_corner;
        }
    }
	for (int i =0; i<m; ++i) {
		for (int j=0; j <n; ++j){
		  printf("%d%s", matrix[i][j], ((j!=n-1)?" ":"\n"));	
        }
	}
}