Fix standard errors

Author: mhihasan

Backtracking/NQueen.js

@@ -1,15 +1,8 @@
-const displayBoard = (board) => {
-  console.log("\n");
-  for (const row of board) {
-    console.log(...row)
-  }
-}
-
 class NQueen {
   constructor (size) {
     this.board = new Array(size).fill('.').map(() => new Array(size).fill('.'))
     this.size = size
-    this.solutions = []
+    this.solutionCount = 0
   }
 
   isValid ([row, col]) {
@@ -33,17 +26,18 @@ class NQueen {
     return true
   }
 
-  placeQueen(row, col){
+  placeQueen (row, col) {
     this.board[row][col] = 'Q'
   }
 
-  removeQueen(row, col){
-    this.board[row][col] = '.';
+  removeQueen (row, col) {
+    this.board[row][col] = '.'
   }
 
   solve (col = 0) {
     if (col >= this.size) {
-      this.solutions.push(JSON.parse(JSON.stringify(this.board)));
+      this.printBoard()
+      this.solutionCount++
       return true
     }
 
@@ -57,19 +51,13 @@ class NQueen {
 
     return false
   }
-}
 
-function main () {
-  const nQueen = new NQueen(4)
-  displayBoard(nQueen.board)
-  nQueen.solve()
-
-  console.log("Number of solutions:", nQueen.solutions.length);
-  nQueen.solutions.forEach((solution)=> {
-    displayBoard(solution)
-  });
+  printBoard () {
+    console.log('\n')
+    for (const row of this.board) {
+      console.log(...row)
+    }
+  }
 }
 
-// main()
-
-export { NQueen };
+export { NQueen }

Backtracking/test/NQueen.test.js

@@ -0,0 +1,15 @@
+import { NQueen } from '../NQueen'
+
+describe('NQueen', () => {
+  it('should return 2 solutions for 4x4 size board', () => {
+    const nQueen = new NQueen(4)
+    nQueen.solve()
+    expect(nQueen.solutionCount).toEqual(2)
+  })
+
+  it('should return 92 solutions for 8x8 size board', () => {
+    const nQueen = new NQueen(8)
+    nQueen.solve()
+    expect(nQueen.solutionCount).toEqual(92)
+  })
+})