Package g1501_1600.s1559_detect_cycles_in_2d_grid

Class Solution

  • public class Solution
extends Object
    1559 - Detect Cycles in 2D Grid.

    Medium

    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.

    • Constructor Detail

      • Solution

        public Solution()

    • Method Detail

      • containsCycle

        public boolean containsCycle​(char[][] grid)