566. Reshape the Matrix

class Solution {
public:
vector<vector<int>> matrixReshape(vector<vector<int>>& nums, int r, int c) {
vector<vector<int>> res(r,vector<int>(c));
int row=nums.size();
if(row==0)return res;
int col=nums[0].size();
if(row*col!=r*c)return nums;

int m=0,n=0;
for(int i=0;i<r;i++)
for(int j=0;j<c;j++)
{
if(n==col-1)//当遍历到最后一列，则行++
{res[i][j]=nums[m]
;
m++;
n=0;
}
else
{   res[i][j]=nums[m]
;//直接向后遍历
n++;
}
}
return res;
}
};