Minesweeper

1 min read Tweet this post
Section titled Problem

Problem

In the game of Minesweeper, the player is presented with a board which contains some mines and cells that don’t have mines. The cells that don’t contain a mine have a number in them that represents the total number of mines in the neighboring cells. The goal is to create a Minesweeper game setup, starting with an initial arrangement of mines on the board.

Section titled Example

Example

For

``````matrix = [[true, false, false],
[false, true, false],
[false, false, false]]``````

the output should be

``````solution(matrix) = [[1, 2, 1],
[2, 1, 1],
[1, 1, 1]]``````

Input/Output

[input] array.array.boolean matrix

A non-empty rectangular matrix consisting of boolean values - true if the corresponding cell contains a mine, false otherwise.

Guaranteed constraints: `2 ≤ matrix.length ≤ 100`, `2 ≤ matrix[0].length ≤ 100`.

[output] array.array.integer

Rectangular matrix of the same size as matrix each cell of which contains an integer equal to the number of mines in the neighboring cells. Two cells are called neighboring if they share at least one corner.

Section titled Solution

Solution

Solving this problem is very straihtforward.

1. Walking through all matrix positions.
2. Check the surrounding cells containing a mine and count all mines in them.
3. Update current cell with total mines in neighbor, include diagonal neighbor.
Section titled Step%201

Step 1

Define all direction to check the neighbor values.

``````func solution(matrix [][]bool) [][]int {
// all directions, including diagonal
allDirections := [][2]int{
{-1, -1}, // diag upper left
{0, -1},  // left
{1, -1},  // diag lower left
{-1, 0},  // up
{1, 0},   // down
{-1, 1},  // diag upper right
{0, 1},   // right
{1, 1},   // diag lower right
}
maxRow, maxCol := len(matrix), len(matrix[0])

// helper func to check bounds of a position in the grid
outOfBounds := func(r, c int) bool {
return r < 0 || r >= maxRow || c >= maxCol || c < 0
}

result:=make([][]int, maxRow)

for row := range matrix{
result[row] = make([]int, maxCol)
for col:= range matrix[row]{
for _, coords := range allDirections {
r,c := coords[0]+row,coords[1]+col
if outOfBounds(r,c) {
continue
}
// if a neighbor is bomb add counter
if matrix[r][c]{
result[row][col]+=1
}
}
}
}

return result
}``````
Section titled Step%202

Step 2

Get max row and column matrix and create helper `outOfBounds` function to check matrix position outside matrix or not.

Section titled Step%203

Step 3

Create place holder result array.

Section titled Step%204

Step 4

Iterate through all matrix.

Section titled Step%205

Step 5

Find the neighbor with bomb:

• if neighbor is out of bounds, ignore
• every a bomb that found in the neighbor, increase 1 value to the current position.

Section titled Step%206

Step 6

Return `result` array

cp go practice