Toeplitz Matrix

Description

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].

Tags: Array

思路

给出一个二维数组，判断每一条左上至右下的对角线上的数是否是一致的。

遍历数组，判断每个数是否与其右下角的数一致即可。注意边界判断。

Java:

public boolean isToeplitzMatrix(int[][] matrix) {
    int h = matrix.length - 1;
    int w = matrix[0].length - 1;
    for (int i = 0; i < h; i++) {
        for (int j = 0; j < w; j++) {
            if (matrix[i][j] != matrix[i + 1][j + 1]) {
                return false;
            }
        }
    }
    return true;
}

结语

如果你同我们一样热爱数据结构、算法、LeetCode，可以关注我们 GitHub 上的 LeetCode 题解：LeetCode-Solution