add source code

8Queens.js

@@ -0,0 +1,62 @@
+let solutionCount = 0;
+function countPrint() {
+	return ++solutionCount;
+}
+
+function buildArrs() {
+	let arrs = [];
+	for (let i=8; i>0; i--) {
+		let arr = [];
+		for (let j=8; j>0; j--) {
+			arr.push(0);	
+		}
+		arrs.push(arr);
+	}
+	return arrs;
+}
+
+function printArrs(arrs) {
+	console.log("------------------------------ count=", countPrint());
+	for (let i=0; i<arrs.length; i++) {
+		let arr = arrs[i];
+		let row = arr.map(item => {
+			return !!item ? ' ● ' : ' ○ ';
+		}).join("");
+		console.log(row);
+	}
+}
+
+function isConflict(arrs, rowIndex, colIndex) {
+	const target = arrs[rowIndex][colIndex];
+	for (let i=rowIndex-1; i>=0; i--) {
+		let row = arrs[i];
+		let j = row.indexOf(1);
+		if (j==colIndex || (rowIndex-i == Math.abs(colIndex-j)))
+			return true;
+	}
+	return false;
+}
+
+function clearDirtyRow(row) {
+	row.fill(0);
+}
+
+function findQueens(arrs, rowIndex) {
+	if (rowIndex>=8) {
+		printArrs(arrs);
+		return;
+	}
+	for (let i=0; i<arrs[rowIndex].length; i++) {
+		if (!isConflict(arrs, rowIndex, i)) { 
+			clearDirtyRow(arrs[rowIndex]);
+			arrs[rowIndex][i] = 1;
+			findQueens(arrs, rowIndex+1);
+		}
+	}
+}
+
+function start() {
+	let plate = buildArrs();
+	solutionCount = 0;
+	findQueens(plate, 0);
+}