reshape the matrix
vector<vector<int>> matrixReshape(vector<vector<int>>& mat, int r, int c) {
int n = mat.size();
int m = mat[0].size();
if(n*m!=r*c)return mat;
//Create a matrix of size r*c
vector<vector<int>> ans(r, vector<int>(c,0));
int x=0,y=0;
for(int i=0;i<n;i++){
for(int j=0;j<m;j++){
ans[x][y] = mat[i][j];
y++;
if(y==c){
y=0;
x++;
}
}
}
return ans;
}