http://codingbat.com/prob/p199368
public boolean groupSum6(int start, int[] nums, int target) {
if( start >= nums.length){
return target==0;
}
if(nums[start]==6){
if( groupSum6(start+1, nums, target-nums[start]) ) return true;
}
else{
if(groupSum6(start+1, nums, target-nums[start])) return true;
if(groupSum6(start+1, nums, target)) return true;
}
return false;
}
