public class Solution
extends Object
1591 - Strange Printer II\.
Hard
There is a strange printer with the following two special requirements:
* On each turn, the printer will print a solid rectangular pattern of a single color on the grid. This will cover up the existing colors in the rectangle.
* Once the printer has used a color for the above operation, **the same color cannot be used again**.
You are given a `m x n` matrix `targetGrid`, where `targetGrid[row][col]` is the color in the position `(row, col)` of the grid.
Return `true` _if it is possible to print the matrix_ `targetGrid`_,_ _otherwise, return_ `false`.
**Example 1:**
**Input:** targetGrid = \[\[1,1,1,1],[1,2,2,1],[1,2,2,1],[1,1,1,1]]
**Output:** true
**Example 2:**
**Input:** targetGrid = \[\[1,1,1,1],[1,1,3,3],[1,1,3,4],[5,5,1,4]]
**Output:** true
**Example 3:**
**Input:** targetGrid = \[\[1,2,1],[2,1,2],[1,2,1]]
**Output:** false
**Explanation:** It is impossible to form targetGrid because it is not allowed to print the same color in different turns.
**Constraints:**
* `m == targetGrid.length`
* `n == targetGrid[i].length`
* `1 <= m, n <= 60`
* `1 <= targetGrid[row][col] <= 60`