(Easy) Backtracking: N-Queen Problems- Algorithm

Description:

 

 

Solution:

class Main {
  public static void main(String[] args) {
    System.out.println("Hello world!");
      int size = 8; 
    
    char [][] map = new char[size][size];
    for(int i =0; i<size; i++){
        for(int j=0; j<size; j++){
            map[i][j] = '-';
        }
    }

  Main m = new Main();

    if(m.Solve(map,0)){
        printSolution(map);
    };

  }

    static void printSolution(char board[][]) 
    { 
        for (int i = 0; i < 8; i++) { 
            for (int j = 0; j < 8; j++) 
                System.out.print(" " + board[i][j] 
                                 + " "); 
            System.out.println(); 
        } 
    } 
    boolean Solve(char[][]map , int cnt){

      if(cnt>=8){
        
        return true;
      }

      for(int tmp = 0; tmp<8; tmp++){

          if(Validate(map,cnt, tmp)){
              map[cnt][tmp]='Q';

              if(Solve(map,cnt+1)){
                return true;
              }else{
                map[cnt][tmp] ='-';
              }
          }
          
      }
      return false;
    }
    public boolean Validate(char[][] map,int i, int j ){
            //column check 
        for(int m = 0; m< map.length; m++){
         
          if(m!=i){
            if(map[m][j]=='Q'){
              return false;
            }
          }
        }
    
        // row check
         for(int k = 0; k<map[0].length;k++){

           if(k!=j){
             if(map[i][k]=='Q'){
               return false;
             }
           }
         }
        // dia1 check
        //(k+l) == (i+j)) || ((k-l) == (i-j)
        for(int m=0; m<map.length; m++){
          for(int k = 0; k<map[0].length; k++){
            if((i+j)==(m+k) || (i-j)==(m-k)){

              if(map[m][k]=='Q'){
                return false;
              }
            }
          }
        }
        return true;
    }
 
}