30:T5b8,{ const { step, count } = currentStep; const initialGrid = parseInput(); const boxBorder = 2; const cellBorder = 1; const rows = step.map((row, i) => { const cells = row.map((digit, j) => { const classNames = `grid__cell${ initialGrid[i][j] ? '' : ' grid__cell_red' }`; const content = digit || ''; return `

${content}

`; }); return `

${cells.join('')}

`; }); return html`

Step: ${count}

${rows}

`; }31:[] 2e:{"title":"Sudoku","cells":[{"id":0,"value":"md`# Sudoku\nAn interactive implementation of a\n[backtracking algorithm](https://en.wikipedia.org/wiki/Sudoku_solving_algorithms#Backtracking)\nsolving a Sudoku.`","pinned":false,"hidden":false,"mode":"ojs"},{"id":2,"value":"{\n const input = DOM.range(1, 100, 1);\n const valueContainer = DOM.element('span');\n valueContainer.innerText = input.value = mutable speedup;\n input.oninput = () => {\n valueContainer.innerText = mutable speedup = input.valueAsNumber;\n };\n return html`\n

Speedup

\n ${input}\n ${valueContainer}`;\n}","pinned":false,"hidden":false,"mode":"ojs"},{"id":6,"value":"viewof replay = html``;","pinned":false,"hidden":false,"mode":"ojs"},{"id":8,"value":"$30","pinned":false,"hidden":false,"mode":"ojs"},{"id":10,"value":"input = `\n53..7....\n6..195...\n.98....6.\n8...6...3\n4..8.3..1\n7...2...6\n.6....28.\n...419..5\n....8..79`;","pinned":false,"hidden":false,"mode":"ojs"},{"id":13,"value":"currentStep = {\n replay;\n let step, count = 0;\n for (step of solve()) {\n count += 1;\n if (showSteps && count % mutable speedup === 0) {\n yield { step, count };\n }\n }\n yield { step, count };\n}","pinned":false,"hidden":false,"mode":"ojs"},{"id":15,"value":"showSteps = true;","pinned":false,"hidden":false,"mode":"ojs"},{"id":17,"value":"mutable speedup = 42;","pinned":false,"hidden":false,"mode":"ojs"},{"id":19,"value":"md`# Solver functions`","pinned":false,"hidden":false,"mode":"ojs"},{"id":21,"value":"function* solve() {\n const state = parseInput();\n const size = state.length;\n\n function* solveFromIndex(index) {\n if (index === size ** 2) {\n return true;\n }\n const i = Math.floor(index / size);\n const j = index % size;\n if (state[i][j]) {\n return (yield* solveFromIndex(index + 1));\n } else {\n for (let k = 1; k <= size; k += 1) {\n state[i][j] = k;\n yield state;\n if (isValid(state) && (yield* solveFromIndex(index + 1))) {\n return true;\n }\n }\n state[i][j] = null;\n return false;\n }\n }\n \n yield* solveFromIndex(0);\n}","pinned":true,"hidden":false,"mode":"ojs"},{"id":23,"value":"function isValid(state) {\n const size = state.length;\n const boxSize = Math.sqrt(size);\n for (let i = 0; i < size; i += 1) {\n const row = [];\n const column = [];\n const box = [];\n const i0 = (i % boxSize) * boxSize;\n const j0 = Math.floor(i / boxSize) * boxSize;\n for (let j = 0; j < size; j += 1) {\n row.push(state[i][j]);\n column.push(state[j][i]);\n const i1 = (j % boxSize);\n const j1 = Math.floor(j / boxSize);\n box.push(state[i0 + i1][j0 + j1]);\n }\n if (!(isUnique(row) && isUnique(column) && isUnique(box))) {\n return false;\n }\n }\n return true;\n}","pinned":true,"hidden":false,"mode":"ojs"},{"id":25,"value":"function isUnique(group) {\n const values = group.filter(value => value !== null);\n return values.length === new Set(values).size;\n}","pinned":true,"hidden":false,"mode":"ojs"},{"id":27,"value":"function parseInput() {\n const rows = input.trim().split('\\n');\n return rows.map(row => row.split('').map(digit => parseInt(digit) || null));\n}","pinned":true,"hidden":false,"mode":"ojs"}],"files":"$W31","stdlib":"1","titling":"auto"}