HackerRank Matrix Rotation - study code - C++ - Good idea to declare global variable with size 300, jagged array

matrixRotation_gg_1.cpp

#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;

int M[300][300];

void R(int m, int n, int d, int r) {
    int x = m - d;
    int y = n - d;
    int c = 2*(x + y) - 4;
    r %= c;
    int xi,yi;
    xi = d >> 1;
    yi = d >> 1;
    
    /*
    int t1=m[xi+x-1][yi];
    int t2=m[xi+x-1][yi+y-1];
    int t3=m[xi][yi+y-1];
    */
    for(int ci=0; ci< r; ci++) {
      int t0=M[xi][yi];
      for(int t=0;  t<(y-1); t++) 
        M[xi][yi+t] = M[xi][yi+t+1];
      for(int t=0; t<(x-1); t++)
        M[xi+t][yi+y-1] = M[xi+t+1][yi+y-1];
      for(int t=0; t<(y-1); t++)
         M[xi+x-1][yi+y-1-t] =M[xi+x-1][yi+y-1-t-1]; 
      for(int t=0; t<(x-2); t++)
         M[xi+x-1-t][yi] = M[xi+x-1-1-t][yi];
      M[xi+1][yi] = t0;      
    }
}

int main() {
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */   
    int m,n,r;
    cin >> m >>n >> r;
    for(int r=0; r<m; r++) {
        for(int c=0; c<n; c++) {
            cin >> M[r][c];
        }
    }
    int x = min(m,n);
    for(int i=0; i<x; i+=2) {
       R(m, n, i, r);
    }

    for(int r=0; r<m; r++) {
        for(int c=0; c<n; c++) {
            cout << M[r][c] << ' ';
        }
        cout << endl;
    }
    cout << endl;
    return 0;
}