[Create] LeetCode_2 두 리스트 더하기

AddTwoListNum/AddTwoNum.java

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+// LeetCode_2
+// 2020.04.12
+// List, case work
+// Medium
+
+public class AddTwoNum {
+    public static void main(String[] args) {
+        new ListNode().printListNode(new AddTwoNum().addTwoNumbers(
+                new ListNode(2, new ListNode(4, new ListNode(3))),
+                new ListNode(5, new ListNode(6, new ListNode(4)))));
+    }
+
+    public ListNode addTwoNumbers(ListNode l1, ListNode l2) throws NumberFormatException{
+        long num1 = 0, num2 = 0;
+        ListNode listNode = new ListNode();
+        ListNode head = listNode;
+
+        while (l1 != null) {
+            num1 += l1.val;
+            if (l1.next != null)
+                num1 *= 10;
+            l1 = l1.next;
+        }
+        while (l2 != null) {
+            num2 += l2.val;
+            if (l2.next != null)
+                num2 *= 10;
+            l2 = l2.next;
+        }
+        StringBuffer str1 = new StringBuffer(String.valueOf(num1));
+        StringBuffer str2 = new StringBuffer(String.valueOf(num2));
+        str1.reverse();
+        str2.reverse();
+        num1 = Long.valueOf(String.valueOf(str1));
+        num2 = Long.valueOf(String.valueOf(str2));
+        num1 += num2;
+
+
+        while (num1 != 0) {
+            listNode.val = num1 % 10;
+            num1 /= 10;
+            if (num1 == 0)
+                break;
+            listNode.next = new ListNode();
+            listNode = listNode.next;
+        }
+
+        return head;
+    }
+}
+
+// Best Solution-O(max(n,m))_출처 leetcode
+//
+//    public ListNode addTwoNumbers(ListNode l1, ListNode l2) {
+//        ListNode dummyHead = new ListNode(0);
+//        ListNode p = l1, q = l2, curr = dummyHead;
+//        int carry = 0;
+//        while (p != null || q != null) {
+//            int x = (p != null) ? p.val : 0;
+//            int y = (q != null) ? q.val : 0;
+//            int sum = carry + x + y;
+//            carry = sum / 10;
+//            curr.next = new ListNode(sum % 10);
+//            curr = curr.next;
+//            if (p != null) p = p.next;
+//            if (q != null) q = q.next;
+//        }
+//        if (carry > 0) {
+//            curr.next = new ListNode(carry);
+//        }
+//        return dummyHead.next;
+//    }

AddTwoListNum/ListNode.java

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+import javax.swing.*;
+
+public class ListNode {
+    long val;
+    ListNode next;
+
+    ListNode() {
+    }
+
+    ListNode(int val) {
+        this.val = val;
+    }
+
+    ListNode(int val, ListNode next) {
+        this.val = val;
+        this.next = next;
+    }
+
+    public void printListNode(ListNode listNode){
+        while(listNode != null){
+            System.out.print(listNode.val+ " ");
+            listNode = listNode.next;
+        }
+    }
+}