//

// Solution48.cpp

// Algorithm

//

// Created by Pancf on 2020/10/25.

// Copyright © 2020 Pancf. All rights reserved.

//

#include "Solution48.hpp"

#include <algorithm>

/* time complexity is n^2 / 2

* 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

*/

void rotate(std::vector<std::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)

std::swap(matrix[i][j], matrix[j][i]);

}

}

/*

* 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

*/

void anti_rotate(std::vector<std::vector<int> > &matrix) {

for (auto vi : matrix) reverse(vi.begin(), vi.end());

for (int i = 0; i < matrix.size(); ++i) {

for (int j = i + 1; j < matrix[i].size(); ++j)

std::swap(matrix[i][j], matrix[j][i]);

}

}

void Solution48::rotate(std::vector<std::vector<int> > &matrix)

{

// (0, 0) -> (0, 3), (0, 3) -> (3, 3), (3, 3) -> (3, 0), (3, 0) -> (0, 0)

// (0, 1) -> (1, 3), (1, 3) -> (3, 2), (3, 2) -> (2, 0), (2, 0) -> (0, 1)

// (0, 2) -> (2, 3), (2, 3) -> (3, 1), (3, 1) -> (1, 0), (1, 0) -> (0, 2)

// (1, 1) -> (1, 2), (1, 2) -> (2, 2), (2, 2) -> (2, 1), (2, 1) -> (1, 1)

int n = (int)matrix.size();

int numberOfCircles = n / 2;

for (int i = 0; i < numberOfCircles; ++i) {

// start at (i, i), end is (i, i + matrix[i].size() - 2 - i)

for (int j = i; j <= std::max(i, n - i - 2); ++j) {

auto temp = matrix[i][j];

matrix[i][j] = matrix[n - j - 1][i];

matrix[n - j - 1][i] = matrix[n - i - 1][n - j - 1];

matrix[n - i - 1][n - j - 1] = matrix[j][n - i - 1];

matrix[j][n - i - 1] = temp;

}

}

}