12. Integer to Roman

Given an integer, convert it to a roman numeral.

Input is guaranteed to be within the range from 1 to 3999.

代码如下：

 public class Solution {
     public String intToRoman(int num) {
         int n=0;
         int[] nums={1000,500,100,50,10,5,1};
         Map<Integer,String> map=new HashMap<>();
         map.put(1,"I");
         map.put(10,"X");
         map.put(100,"C");
         map.put(1000,"M");
         map.put(5,"V");
         map.put(50,"L");
         map.put(500,"D");
         String s="";
         if(map.containsKey(num))
         return map.get(num);

       for(int i=0;i<nums.length-1;i++)
         {
             if(num>=nums[i])
             {
                 n=num/nums[i];

                  if(n>=1&&n<=4){
                      if(n==4)
                      {
                          if(s.length()!=0&&s.substring(s.length()-1,s.length()).equals(nums[i-1]))
                          {
                              s=s.substring(0,s.length()-1);
                              s=s+map.get(nums[i]);

                              if(nums[i]==10||nums[i]==100)
                              s=s+map.get(nums[i-2]);
                          }else{
                              s=s+map.get(nums[i]);
                              if(nums[i]==10||nums[i]==100)
                               s=s+map.get(nums[i-1]);
                          }
                      }
                      else{
                          while(n>0)
                           {s=s+map.get(nums[i]);n--;}
                      }
                      num=num%nums[i];
                  }
             }
         }
         n=num/nums[nums.length-1];
          if(n>=1&&n<=4){
              if(n==4)
              {s=s+map.get(nums[nums.length-1])+map.get(nums[nums.length-2]);}
              else{
                  while(n>0)
                  {s=s+map.get(nums[nums.length-1]);n--;}
          }
              }
          s=s.replace("VIV","IX");
          s=s.replace("LXL","XC");
          s=s.replace("DCD","CM");
         return s;
     }
 }