class Solution {

public:

void rotate(vector<vector<int>>& matrix) {

recursionRotate(matrix, 0, matrix.size());

return;

}

void recursionRotate(vector<vector<int>>& matrix, int start, int length)

{

int endPos = start + length - 1;

if(length <= 1)

return;

else

{

for(int i = 0; i < length - 1; i++)

{

int tmp = matrix[start][start + i];

matrix[start][start + i] = matrix[endPos - i][start];

matrix[endPos - i][start] = matrix[endPos][endPos - i];

matrix[endPos][endPos - i] = matrix[start + i][endPos];

matrix[start + i][endPos] = tmp;

}

recursionRotate(matrix, start + 1, length - 2);

}

return;

}

};