Rotate
LC48. Rotate Image
🟡lc48
A common method to solve the image rotation problem.
/*
* clockwise rotate
* first reverse up to down, then swap the symmetry
* 1 2 3 7 8 9 7 4 1
* 4 5 6 => 4 5 6 => 8 5 2
* 7 8 9 1 2 3 9 6 3
*/
/*
* anticlockwise rotate
* first reverse left to right, then swap the symmetry
* 1 2 3 3 2 1 3 6 9
* 4 5 6 => 6 5 4 => 2 5 8
* 7 8 9 9 8 7 1 4 7
*/
func rotate(matrix [][]int) {
for i, j := 0, len(matrix)-1; i < j; i, j = i+1, j-1 {
matrix[i], matrix[j] = matrix[j], matrix[i]
}
for i := 0; i < len(matrix); i++ {
for j := i + 1; j < len(matrix[i]); j++ {
matrix[i][j], matrix[j][i] = matrix[j][i], matrix[i][j]
}
}
}void rotate(vector<vector<int> > &matrix) {
reverse(matrix.begin(), matrix.end());
for (int i = 0; i < matrix.size(); ++i) {
for (int j = i + 1; j < matrix[i].size(); ++j)
swap(matrix[i][j], matrix[j][i]);
}
}impl Solution {
pub fn rotate(matrix: &mut Vec<Vec<i32>>) {
matrix.reverse();
for i in 0..matrix.len() {
for j in i+1 .. matrix[i].len() {
let tmp = matrix[i][j];
matrix[i][j] = matrix[j][i];
matrix[j][i] = tmp;
}
}
}
}