From 2fcb682f26b614ed39e88e0ff63ea54a4e5856d3 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Sebasti=C3=A1n=20Santisi?= <s@ntisi.com.ar>
Date: Tue, 7 May 2024 17:46:58 +0000
Subject: [PATCH] Random solutions to 10-queens problem

---
 queens.html | 96 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 96 insertions(+)
 create mode 100644 queens.html

diff --git a/queens.html b/queens.html
new file mode 100644
index 0000000..7321b46
--- /dev/null
+++ b/queens.html
@@ -0,0 +1,96 @@
+<script>
+   function nQueen(boolArrBoard,row){
+       if(row === boolArrBoard.length){
+           display(boolArrBoard)
+           return 1 //count*
+       }
+   
+       let count = 0
+       //placing the queen and checking every row and column*
+       for(let col_ = 0; col_ < boolArrBoard.length; col_++){
+			let col = indexes[col_];
+           //place the queen if it is safe *
+           if(isSafe(boolArrBoard,row,col)){
+               boolArrBoard[row][col] = true
+               count += nQueen(boolArrBoard,row+1)
+				if(count) return 1;
+               boolArrBoard[row][col] = false
+           }
+       }
+       return count
+   }
+   
+   function isSafe(boolArrBoard,row,col){
+       //vertical*
+       for(let i = 0; i < row; i++){
+          if(boolArrBoard[i][col]){
+           return false
+          }
+       }
+   
+       //left diagonal*
+       let maxLeft = Math.min(row,col)
+       for(let i = 1; i <= maxLeft; i++){
+           if(boolArrBoard[row - i][col - i]){
+               return false
+              }
+       }
+   
+       //right diagonal*
+       let maxRight = Math.min(row, boolArrBoard.length - col - 1)
+       for(let i = 1; i <= maxRight; i++){
+           if(boolArrBoard[row - i][col + i]){
+               return false
+              }
+       }
+   
+       return true
+   }
+   function display(boolArrBoard){
+	let div = document.getElementById("solution");
+	div.innerHTML = "";
+       for( let row in boolArrBoard){
+           for(let column in boolArrBoard[row]){
+               if(boolArrBoard[row][column]){
+                   div.append('O ')
+               }
+               else{
+                   div.append('+ ')
+               }
+           }
+           div.append('\n')
+       }
+   }
+
+function shuffle(array) {
+  let currentIndex = array.length;
+
+  // While there remain elements to shuffle...
+  while (currentIndex != 0) {
+
+    // Pick a remaining element...
+    let randomIndex = Math.floor(Math.random() * currentIndex);
+    currentIndex--;
+
+    // And swap it with the current element.
+    [array[currentIndex], array[randomIndex]] = [
+      array[randomIndex], array[currentIndex]];
+  }
+}
+
+var indexes;
+function generar() {
+   let n = 10
+   let boolArrBoard = Array.from({length: n}, () => {
+       return new Array(n).fill(false)
+   })
+   indexes = Array(n).fill().map((x,i)=>i)
+   shuffle(indexes);
+   nQueen(boolArrBoard,0)
+}
+</script>
+<pre id="solution"></pre>
+<button onclick="generar()">¡Generar!</button>
+<script>
+generar();
+</script>