README_EN.md

1886. Determine Whether Matrix Can Be Obtained By Rotation

中文文档

Description

Given two n x n binary matrices mat and target, return true if it is possible to make mat equal to target by rotating mat in 90-degree increments, or false otherwise.

 

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.

Solutions

Python3

class Solution:
    def findRotation(self, mat: List[List[int]], target: List[List[int]]) -> bool:
        def rotate(matrix):
            n = len(matrix)
            for i in range(n // 2):
                for j in range(i, n - 1 - i):
                    t = 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] = t
        for _ in range(4):
            if mat == target:
                return True
            rotate(mat)
        return False

Java

class Solution {
    public boolean findRotation(int[][] mat, int[][] target) {
        int times = 4;
        while (times-- > 0) {
            if (equals(mat, target)) {
                return true;
            }
            rotate(mat);
        }
        return false;
    }
    
    private void rotate(int[][] matrix) {
        int n = matrix.length;
        for (int i = 0; i < n / 2; ++i) {
            for (int j = i; j < n - 1 - i; ++j) {
                int t = 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] = t;
            }
        }
    }
    
    private boolean equals(int[][] nums1, int[][] nums2) {
        int n = nums1.length;
        for (int i = 0; i < n; ++i) {
            for (int j = 0; j < n; ++j) {
                if (nums1[i][j] != nums2[i][j]) {
                    return false;
                }
            }
        }
        return true;
    }
}

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