Toeplitz Matrix

README.md

@@ -69,6 +69,7 @@ A collection of JavaScript problems and solutions for studying algorithms.
 - [Maximum Product of Word Lengths](src/array/maximum-product-of-word-lengths.js)
 - [Kth Largest Element in an Array](src/array/kth-largest-element-in-an-array.js)
 - [Insert Interval](src/array/insert-interval.js)
+- [Toeplitz Matrix](src/array/toeplitz-matrix.js)
 
 ### Matrix
 

src/array/toeplitz-matrix.js

@@ -0,0 +1,62 @@
+/**
+ * Toeplitz Matrix
+ *
+ * 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:
+ *
+ * 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].
+ *
+ * Follow up:
+ *
+ * 1. What if the matrix is stored on disk, and the memory is limited
+ *    such that you can only load at most one row of the  * matrix into the memory at once?
+ * 2. What if the matrix is so large that you can only load up a partial row into the memory at once?
+ */
+
+/**
+ * @param {number[][]} matrix
+ * @return {boolean}
+ */
+const isToeplitzMatrix = matrix => {
+  for (let i = 0; i < matrix.length - 1; i++) {
+    for (let j = 0; j < matrix[0].length - 1; j++) {
+      if (matrix[i][j] !== matrix[i + 1][j + 1]) {
+        return false;
+      }
+    }
+  }
+
+  return true;
+};