组合各种情况,效率低下

class Solution {
    public String intToRoman(int x) {
        Map<Integer, String> dict = new HashMap();
        dict.put(1, "I");
        dict.put(2, "II");
        dict.put(3, "III");
        dict.put(4, "IV");
        dict.put(5, "V");
        dict.put(6, "VI");
        dict.put(7, "VII");
        dict.put(8, "VIII");
        dict.put(9, "IX");
        dict.put(10, "X");
        dict.put(40, "XL");
        dict.put(50, "L");
        dict.put(90, "XC");
        dict.put(100, "C");
        dict.put(400, "CD");
        dict.put(500, "D");
        dict.put(900, "CM");
        dict.put(1000, "M");

        String res = "";
        int high = 0;
        while(x>0){
            if(x/1000>0) {
                    high = x/1000;
                    while(high-->0) res += dict.get(1000);
                    x = x%1000;
            }
            if(x/100>0){
                    high = x/100; 
                    if(high == 9) res += dict.get(900); 
                    else if(high == 5) res += dict.get(500);
                    else if(high == 4) res += dict.get(400);
                    else {
                        if(high > 5) {
                            res += dict.get(500); 
                            high -= 5; 
                        }
                        while(high-->0){
                            res += dict.get(100);
                        }
                    }
                    x = x%100;
            }
            if(x/10>0){
                high = x/10; 
                if(high == 9) res += dict.get(90); 
                else if(high == 5) res += dict.get(50);
                else if(high == 4) res += dict.get(40);
                else {
                        if(high > 5) {
                            res += dict.get(50); 
                            high -= 5; 
                        }
                        while(high-->0){
                            res += dict.get(10);
                        }
                    }
                x = x%10;
            }
            if(x<10 && x>0){res += dict.get(x); x = x%x;}
        }
        return res;
    }
}