var TEST = function () {

    function _original(l1, l2) {
        let sum = NaN;
		let isAdd = false;
		
		let isNode1Exist = true;
		let isNode2Exist = true;
		let someOneIsNull = false;
        while (isNode1Exist || isNode2Exist) {
			isNode1Exist = isNode1Exist && !!l1;
			isNode2Exist = isNode2Exist && !!l2;
			
			sum = isAdd ? 1 : 0;
            sum += isNode1Exist ? l1.val : 0;
			sum += isNode2Exist ? l2.val : 0;
			
			isAdd = sum >= 10;
			if (isAdd) {
				sum-=10;
			}
			
			if (isNode1Exist) {
				l1.val = sum;
				if (someOneIsNull && !l1.next) {
					l1.next = isAdd ? new ListNode(1) : null;
					return true;
				}
				l1 = l1.next;
				someOneIsNull = someOneIsNull || !l1;
			}
			if (isNode2Exist) {
				l2.val = sum;
				if (someOneIsNull && !l2.next) {
					l2.next = isAdd ? new ListNode(1) : null;
					return false;
				}
				l2 = l2.next;
				someOneIsNull = someOneIsNull || !l2;
			}
        }
    }
    
    function _recursionAdd(rtnNode, l1, l2) {
        if (l1) {
            rtnNode.val += l1.val;
            l1 = l1.next;
        }
        if (l2) {
            rtnNode.val += l2.val;
            l2 = l2.next;
        }
        
        if (rtnNode.val >= 10) {
            rtnNode.val -= 10;
            rtnNode.next = _add(new ListNode(1), l1, l2);
        } else if  (l1 && l2) {
            rtnNode.next = _add(new ListNode(0), l1, l2);
        } else {
            if (l1) {
                rtnNode.next = l1;
            } else if (l2) {
                rtnNode.next = l2;
            }
        }
        return rtnNode;
    }
    
    return {
        exec: function (l1, l2) {
            
            // ==== Recursion ====
            /* return _original(l1, l2) ? l1 : l2; */
            
            // ==== Recursion ====
            /*
            return _recursionAdd(new ListNode(0), l1, l2);
            */
            
            // ==== while loop ====
            /*
            let rtnNode = new ListNode(0);
            let ptrNode = rtnNode;
            while (true) {
                if (l1) {
                    ptrNode.val += l1.val;
                    l1 = l1.next;
                }
                if (l2) {
                    ptrNode.val += l2.val;
                    l2 = l2.next;
                }
                
                if (ptrNode.val >= 10) {
                    ptrNode.val -= 10;
                    ptrNode.next = new ListNode(1);
                    ptrNode = ptrNode.next;
                } else if  (l1 && l2) {
                    ptrNode.next = new ListNode(0);
                    ptrNode = ptrNode.next;
                } else {
                    if (l1) {
                        ptrNode.next = l1;
                    } else if (l2) {
                        ptrNode.next = l2;
                    }
                    break;
                }
            }
            return rtnNode;
            */
        }
    };
}();