Given a 2D array of characters `grid` of size `m x n`, you need to find if there exists any cycle consisting of the same value in `grid`.

A cycle is a path of length 4 or more in the grid that starts and ends at the same cell. From a given cell, you can move to one of the cells adjacent to it - in one of the four directions (up, down, left, or right), if it has the same value of the current cell.

Also, you cannot move to the cell that you visited in your last move. For example, the cycle `(1, 1) -> (1, 2) -> (1, 1)` is invalid because from `(1, 2)` we visited `(1, 1)` which was the last visited cell.

Return `true` if any cycle of the same value exists in `grid`, otherwise, return `false`.

Example 1:

    Input: grid = [["a","a","a","a"],["a","b","b","a"],["a","b","b","a"],["a","a","a","a"]]
    Output: true
    Explanation: There are two valid cycles shown in different colors in the image below:

Example 2:

    Input: grid = [["c","c","c","a"],["c","d","c","c"],["c","c","e","c"],["f","c","c","c"]]
    Output: true
    Explanation: There is only one valid cycle highlighted in the image below:

Example 3:

    Input: grid = [["a","b","b"],["b","z","b"],["b","b","a"]]
    Output: false

Constraints:

- `m == grid.length`
- `n == grid[i].length`
- `1 <= m, n <= 500`
- `grid` consists only of lowercase English letters.