Example 1:

Input: mat = [[0,1],[1,0]], target = [[1,0],[0,1]]
Output: true
Explanation: We can rotate mat 90 degrees clockwise to make mat equal target.

Example 2:

Input: mat = [[0,1],[1,1]], target = [[1,0],[0,1]]
Output: false
Explanation: It is impossible to make mat equal to target by rotating mat.

Example 3:

Input: mat = [[0,0,0],[0,1,0],[1,1,1]], target = [[1,1,1],[0,1,0],[0,0,0]]
Output: true
Explanation: We can rotate mat 90 degrees clockwise two times to make mat equal target.

Constraints:

• n == mat.length == target.length
• n == mat[i].length == target[i].length
• 1 <= n <= 10
• mat[i][j] and target[i][j] are either 0 or 1.

Solution: Simulation

Time complexity: O(n²)
Space complexity: O(1)

// Author: Huahua
class Solution {
public:
  bool findRotation(vector<vector<int>>& mat, vector<vector<int>>& target) {    
    const int n = mat.size();
    auto rot = [n](vector<vector<int>>& mat) {      
      for (int i = 0; i < n; ++i)
        for (int j = i; j < n; ++j)
          swap(mat[i][j], mat[j][i]);
      for (int j = 0; j < n; j++)
        for (int i = 0; i < n / 2; ++i)
          swap(mat[i][j], mat[n - i - 1][j]);
      return mat;
    };
    for (int i = 0; i < 4; ++i)
      if (rot(mat) == target) return true;    
    return false;
  }
};

The post 花花酱 LeetCode 1886. Determine Whether Matrix Can Be Obtained By Rotation appeared first on Huahua's Tech Road.