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:
In the above grid, the diagonals are:
“[9]”, “[5, 5]”, “[1, 1, 1]”, “[2, 2, 2]”, “[3, 3]”, “[4]”.
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:
matrix will be a 2D array of integers.
matrix will have a number of rows and columns in range [1, 20].
matrix[i][j] will be integers in range [0, 99].
题意：给定一个二位的矩阵，判断矩阵是否是Toeplitz，当且仅当满足矩阵的同一条对角线上的元素都相同;
解法：我们要比较同一条对角线上的元素是相同的，就是比较当前元素和这个对角线上的上一个元素相同;
class Solution {
public boolean isToeplitzMatrix(int[][] matrix) {
if (matrix.length == 1 && matrix[0].length == 1) {
return true;
}//only one element
for(int i=1; i<matrix.length; i++) {
for(int j=1; j<matrix[i].length; j++) {
if (matrix[i][j] != matrix[i-1][j-1]) {
return false;
}
}
}
return true;
}
}