leetcode 048 Rotate Image

You are given an n x n 2D matrix representing an image.

Rotate the image by 90 degrees (clockwise).

Follow up:

Could you do this in-place?

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class Solution {
public:
void rotate(vector<vector<int>>& matrix) {
int rows = matrix.size(), cols = matrix[0].size();

int uprow = 0, downrow = rows-1, leftcol = 0, rightcol = cols-1;

for(; uprow < downrow; uprow++, downrow--) {
int ax = uprow, ay = leftcol;
int bx = uprow, by = rightcol;
int cx = downrow, cy = leftcol;
int dx = downrow, dy = rightcol;

int cnt = downrow-uprow;

while(cnt--) {

int temp = matrix[bx][by];
matrix[bx][by] = matrix[ax][ay];
matrix[ax][ay] = matrix[cx][cy];
matrix[cx][cy] = matrix[dx][dy];
matrix[dx][dy] = temp;

ay+=1;
bx+= 1;
cx-=1;
dy-=1;
}

leftcol++;
rightcol--;

}
}
};