[LeetCode] 766. Toeplitz Matrix

轉自LeetCode

A matrix is Toeplitz if every diagonal from top-left to bottom-right has the same element.

Now given an M x N matrix, return True if and only if the matrix is Toeplitz.

Example 1:

Input: matrix = [[1,2,3,4],[5,1,2,3],[9,5,1,2]]
Output: True
Explanation:
1234
5123
9512

In the above grid, the diagonals are "[9]", "[5, 5]", "[1, 1, 1]", "[2, 2, 2]", "[3, 3]", "[4]", and in each diagonal all elements are the same, so the answer is True.

Example 2:

Input: matrix = [[1,2],[2,2]]
Output: False
Explanation:
The diagonal "[1, 2]" has different elements.

Note:

1. matrix will be a 2D array of integers.
2. matrix will have a number of rows and columns in range [1, 20].
3. matrix[i][j] will be integers in range [0, 99].

<Solution>

想法如下

• 根據題意，從左上至右下檢查即可

code 如下

Java

	class Solution {
	public boolean isToeplitzMatrix(int[][] matrix) {
	final int row = matrix.length;
	final int col = matrix[0].length;
	for(int r = 0; r < row; r++) {
	for(int c = 0; c < col; c++) {
	if(r > 0 && c > 0 && matrix[r-1][c-1] != matrix[r][c]) {
	return false;
	}
	}
	}
	return true;
	}
	}

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