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Commit c423e6e

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Merge pull request TheAlgorithms#619 from mhihasan/update_nqeen_algo [TheAlgorithms#617]
Find all the solutions of NQueen
2 parents a9b1f89 + e9fd4a9 commit c423e6e

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2 files changed

+34
-21
lines changed

2 files changed

+34
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‎Backtracking/NQueen.js‎

Lines changed: 19 additions & 21 deletions
Original file line numberDiff line numberDiff line change
@@ -2,6 +2,7 @@ class NQueen {
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constructor (size) {
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this.board = new Array(size).fill('.').map(() => new Array(size).fill('.'))
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this.size = size
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this.solutionCount = 0
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}
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isValid ([row, col]) {
@@ -25,41 +26,38 @@ class NQueen {
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return true
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}
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29+
placeQueen (row, col) {
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this.board[row][col] = 'Q'
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}
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removeQueen (row, col) {
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this.board[row][col] = '.'
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}
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solve (col = 0) {
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// function to solve the board
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if (col >= this.size) { return true }
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if (col >= this.size) {
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this.printBoard()
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this.solutionCount++
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return true
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}
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3244
for (let i = 0; i < this.size; i++) {
3345
if (this.isValid([i, col])) {
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this.board[i][col] = 'Q'
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if (this.solve(col + 1)) { return true }
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// backtracking
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this.board[i][col] = '.'
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this.placeQueen(i, col)
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this.solve(col + 1)
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this.removeQueen(i, col)
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}
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}
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return false
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}
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printBoard () {
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// utility function to display the board
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console.log('\n')
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for (const row of this.board) {
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console.log(...row)
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}
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}
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}
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54-
function main () {
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const board = new NQueen(8)
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board.printBoard()
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console.log('\n')
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board.solve()
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board.printBoard()
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}
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main()
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export { NQueen }

‎Backtracking/tests/NQueen.test.js‎

Lines changed: 15 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,15 @@
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import { NQueen } from '../NQueen'
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describe('NQueen', () => {
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it('should return 2 solutions for 4x4 size board', () => {
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const _4Queen = new NQueen(4)
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_4Queen.solve()
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expect(_4Queen.solutionCount).toEqual(2)
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})
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it('should return 92 solutions for 8x8 size board', () => {
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const _8Queen = new NQueen(8)
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_8Queen.solve()
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expect(_8Queen.solutionCount).toEqual(92)
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})
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})

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