give an array and target value, find the max length of the subarray which sum of the elements is less or equal to that value. 

    public int longestSubArray(int[] a, int k){        if(a==null || a.length==0){            return 0;        }        int max=0;        int len=a.length;        for(int i=0; i<len; i++){            int start=a[i];            if(start >= k){                if(max<1){                    max=1;                }            }            else{                int sum=start;                for(int j=i+1; j<len; j++){                    sum=sum+a[j];                    if(sum>k){                        if(max<(j-i)){                            max=j-i;                        }                        break;                    }                                        if(sum <= k && j==(len-1)){                        if(max<(j-i+1)){                            max=j-i+1;                        }                    }                }            }        }        return max;    }