/*     * 339. Nested List Weight Sum     * 2016-7-10 by Mingyang     * 这就是很简单的dfs了，不详谈，count+1不是count++     */    public int depthSum(List
     
       nestedList) {        if(nestedList==null||nestedList.size()==0)          return 0;        return depthSumHelper(nestedList,1);     }     public int depthSumHelper(List
      
        nestedList,int count){         int res=0;         for(NestedInteger nest:nestedList){            if(nest.isInteger()){                res+=count*nest.getInteger();            }else{                List
       
         temp=nest.getList();                res+=depthSumHelper(temp,count+1);            }         }          return res;     }  // This is the interface that allows for creating nested lists.  // You should not implement it, or speculate about its implementation      public interface NestedInteger {  // @return true if this NestedInteger holds a single integer, rather than a nested list.          public boolean isInteger();   // @return the single integer that this NestedInteger holds, if it holds a single integer // Return null if this NestedInteger holds a nested list          public Integer getInteger();      // @return the nested list that this NestedInteger holds, if it holds a nested list // Return null if this NestedInteger holds a single integer          public List
        
          getList();      }