Grokking Graph Algorithms for Coding Interviews
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Coloring A Border (medium)
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Problem Statement

Examples

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Problem Statement

You are given an m x n integers grid, and three integers row, col, and color. Each cell in the grid has a color value represented by an integer.

Two cells are adjacent if they share a side. Cells with the same color and connected through adjacent cells form a connected component.

Color the border of the connected component that includes the cell at grid[row][col] with the new color provided. The border of a connected component consists of cells that are either adjacent to a cell with a different color or lie on the boundary of the grid.

Return the modified grid after coloring the border.

Examples

Example 1:

  • Input: row = 1, col = 1, color = 3, grid =
[[1, 2, 2], 
 [2, 2, 2], 
 [1, 2, 1]]
  • Expected Output: [[1, 3, 3], [3, 2, 3], [1, 3, 1]]
Image
  • Justification: The connected component includes all cells. The border cells are colored with 1.

Example 2:

  • Input: row = 2, col = 0, color = 1, grid =
[[2, 2, 2], 
 [2, 2, 2], 
 [2, 2, 2]]
  • Expected Output: [[1, 1, 1], [1, 2, 1], [1, 1, 1]]
Image
  • Justification: The connected component includes all cells. The border cells are colored with 1.

Example 3:

  • Input: row = 1, col = 2, color = 4, grid =
[[1, 1, 1, 1], 
 [1, 1, 2, 2], 
 [1, 1, 2, 2]]
  • Expected Output: [[1, 1, 1, 1], [1, 1, 4, 4], [1, 1, 4, 4]]
Image
  • Justification: The connected component is the block of 2s. The border cells of this block are colored with 4.

Constraints:

  • m == grid.length
  • n == grid[i].length
  • 1 <= m, n <= 50
  • 1 <= grid[i][j], color <= 1000
  • 0 <= row < m
  • 0 <= col < n

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Python3
Python3
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Problem Statement

Examples

Try it yourself