Today I went through a standard coding challenge: “Create a minesweeper board with variable rows, columns, and bombs”. The challenge was for 20 minutes, spent 31 minutes, and cannot really figure out why it could never generate.<\/p>\n\n\n\n
After my previous posting of “omg my server didn’t have virtual memory” I decided to fiddle it out. With my own fingers this took 12 minutes tops, but the amount of regret I feel is priceless.<\/p>\n\n\n\n\n\n\n\n
function makeMinesweeperBoard(rows = 5, cols = 5, mines = 5) {\n var board = [];\n \/* Make a blank board with 0s *\/\n for (let r = 0; r < rows; r++) {\n \tlet l = new Array();\n \tfor (let c= 0 ; c < cols; c++) {\n \tl.push('0');\n }\n board.push(l);\n }\n \/* Fill board with mines, aka Xs *\/\n while (mines > 0) {\n \tlet c = Math.floor(Math.random() * cols);\n let r = Math.floor(Math.random() * rows);\n if (board[r][c] == 'X') { continue; }\n board[r][c] = 'X';\n mines--;\n }\n \/* Put the numbers where they need to be *\/\n for (let r = 0; r < rows; r++) {\n \tfor (let c = 0; c < cols; c++) {\n \tif (board[r][c] == 'X') { continue; }\n \tlet totalMines = 0;\n for (let x = -1; x <= 1; x++) {\n \tfor (let y = -1; y <= 1; y++) {\n \tif ((r + x) < 0) { continue; }\n if ((c + y) < 0) { continue; }\n if ((r + x) >= rows) { continue; }\n if ((c + y) >= cols) { continue; }\n \tif (board[r + x][c + y] == \"X\") {\n \ttotalMines++;\n }\n }\n }\n board[r][c] = totalMines.toString();\n }\n }\n return board;\n}\n\nconsole.log(makeMinesweeperBoard());<\/code><\/pre>\n\n\n\nThe first mistake was in board\/array generation. The clue was specifically on the screen in that an array of Objects were created when I needed an array of arrays. I also misused Array.prototype.fill() in my derpiness and ended up on Round 2 just hand-pushing my 0s.<\/p>\n\n\n\n
Second mistake was on mine laying. I didn’t check if the space actually had a mine or not, so when actually generating a specific number of mines it had a 1 in rows*cols chance of duplicating.<\/p>\n\n\n\n
Third mistake was in the mine counting. I made my tester aware that it would exceed array bounds and I felt a bit under pressure (since time was ticking down) to remedy it.<\/p>\n\n\n\n
Regardless it took me less than 20 minutes to jsfiddle this solution together with my own fingers and console.log()’s.<\/p>\n\n\n\n