EightQueens

function EightQueens(){
    const sol = new Array(8).fill(-1);
    const solutions = [];
    function IsSafe(row,col){
      for (let i = 0; i < row; i++) {
        //col
        if(sol[i] === col){
          return false;
        }
        //斜線
        if(Math.abs(sol[i] - col) === Math.abs(i - row)){
          return false;
        }
      }
      return true;
    }
    function Solve(startRow){
      if(startRow===8){
        solutions.push([...sol]);
        return;
      }
      for(let col = 0;col<8;col++){
        if(IsSafe(startRow,col)){
          sol[startRow]=col;
          Solve(startRow+1);
        }
      }
    }
    function PrintSolutions(){
        for(let i = 0;i<solutions.length;i++){
          const header = 'Solution:'+(i+1).toString();
          console.log(header);
          const s=solutions[i];
          
          for(let row = 0;row<8;row++){
            let rowString = "";
            for(let col=0;col<8;col++){
              if(col===s[row]){
                rowString += 'Q';
              }else{
                rowString += '.';
              }
            }
            console.log(rowString);
          }
        }
    }
    Solve(0);
    PrintSolutions();
}
EightQueens();