51. N-Queens

https://leetcode.com/problems/n-queens/

N-Queens - LeetCode

/**
 * @param {number} n
 * @return {string[][]}
 */
var solveNQueens = function(n) {
    var map = Array(n).fill(-1);
    var res = [];
    //var hash= {};
    
    var colhash = Array(n).fill(0);
    
    var save_map = function()
    {
        var tmp = [];
        for( var i=0; i<n; ++i )
        {
            var Qpos = map[i];
            var row = [];
            for( var j=0; j<n; ++j )
            {
                if( j == Qpos)      row.push("Q");
                else                row.push(".");
            }
            tmp.push(row.join(''));
        }
        res.push(tmp);
    }
    
    var chk = function()
    {        
        for( var i=0; i<n; ++i )
        {            
            for( var j=1; j<n-i; ++j )
            {                
                // 우하                
                {
                    if( map[i]+j == map[i+j] || map[i]-j == map[i+j] )
                        return false;
                }                
                
                // 좌하
                if( i-j > 0 )
                {
                    if( map[i]+j == map[i-j] || map[i]-j == map[i-j] )
                        return false;
                }
            }            
        }        
       
        return true;
    }
    
    var find = function( p_idx )
    {
        if( p_idx == n )
        {            
            if( chk() )     save_map();              
        }
        else
        {
            for( var i=0; i<n; ++i )
            {
                if( !colhash[i] )
                {
                    colhash[i] = 1;

                    map[p_idx]= i;                
                    if( p_idx+1 <= n )      find(p_idx+1);                
                    map[p_idx]= -1;

                    colhash[i] = 0;
                }            
            }
        }        
    }
    
    find(0);
    
    
    return res;
};