v10

test/algorithm/linked_list/02_link_list_add.dart

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+/// 两数相加
+// 给你两个非空的链表表示两个非负的整数。
+// 它们每位数字都是按照逆序 的方式存储的，并且每个节点只能存储一位数字
+
+//  请你将两个数相加，并以相同形式返回一个表示和的链表。
+// 你可以假设除了数字  之外，这两个数都不会以  开头。
+//输入: 1=[2,4,3]， 2=[5,6,4] 输出:[7,0,8] 解释: 342 + 465 = 807.
+void main() {
+  // l1 = [9,9,9,9,9,9,9], l2 = [9,9,9,9]
+  ListNode l1 = ListNode(2, next: ListNode(4, next: ListNode(3)),);
+  ListNode l2 = ListNode(5, next: ListNode(6, next: ListNode(4)),);
+
+  //9,9,9,9,9,9,9
+  // ListNode l1 = ListNode(9, next: ListNode(9, next: ListNode(9, next: ListNode(9, next: ListNode(9, next: ListNode(9, next: ListNode(9, next: ListNode(9, next: ListNode(9)))))))));
+  // ListNode l2 = ListNode(9, next: ListNode(9, next: ListNode(9,next: ListNode(9)),));
+  ListNode result = addTwoNumbers(l1, l2);
+  print(result);
+}
+
+class ListNode {
+  int val;
+  ListNode? next;
+
+  ListNode(this.val, {this.next});
+
+  @override
+  String toString(){
+    String result='';
+    ListNode? cur = this;
+    while(cur!=null){
+      result += cur.val.toString();
+      cur = cur.next;
+    }
+    return result;
+  }
+
+}
+
+// ListNode? addTwoNumbers(ListNode? l1, ListNode? l2) {
+//   if (l1 == null) {
+//     return l2;
+//   }
+//   if (l2 == null) {
+//     return l1;
+//   }
+//   ListNode? l3 = ListNode(0);
+//   ListNode? cur = l3;
+//   int temp = 0;
+//   while (l1 != null || l2 != null) {
+//     int val1 = l1 == null ? 0 : l1.val;
+//     int val2 = l2 == null ? 0 : l2.val;
+//     int sum = val1 + val2 + temp;
+//     cur?.next = ListNode(sum % 10);
+//     temp = sum ~/ 10;
+//     cur = cur?.next;
+//     l1 = l1?.next;
+//     l2 = l2?.next;
+//   }
+//   if (temp != 0) {
+//     cur?.next = ListNode(temp);
+//   }
+//   return l3.next;
+// }
+
+// ListNode? addTwoNumbers(ListNode? l1, ListNode? l2) {
+//   ListNode? head, tail;
+//   int carry = 0;
+//   while (l1 != null || l2 != null) {
+//     int n1 = l1?.val ?? 0;
+//     int n2 = l2?.val ?? 0;
+//     int sum = n1 + n2 + carry;
+//     if (head == null) {
+//       head = ListNode(sum % 10);
+//       tail = head;
+//     } else {
+//       tail!.next = ListNode(sum % 10);
+//       tail = tail.next;
+//     }
+//     carry = sum ~/ 10;
+//     l1 = l1?.next;
+//     l2 = l2?.next;
+//   }
+//   if (carry > 0) {
+//     tail!.next = ListNode(carry);
+//   }
+//   return head;
+// }
+
+ListNode addTwoNumbers(ListNode? l1, ListNode? l2) {
+  ListNode pre = ListNode(0);
+  ListNode cur = pre;
+  int carry = 0;
+  while (l1 != null || l2 != null) {
+    int x = l1?.val ?? 0;
+    int y = l2?.val ?? 0;
+    int sum = x + y + carry;
+
+    carry = sum ~/ 10;
+    sum = sum % 10;
+    cur.next = ListNode(sum);
+
+    cur = cur.next!;
+    if (l1 != null) {
+      l1 = l1.next;
+    }
+    if (l2 != null) {
+      l2 = l2.next;
+    }
+  }
+  if (carry == 1) {
+    cur.next = ListNode(carry);
+  }
+  return pre.next!;
+}

test/algorithm/linked_list/206_reverse_list.dart

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+
+void main(){
+  /// 打印 1->9->9->4
+  ListNode listNode = ListNode(1, ListNode(9, ListNode(9,ListNode(4))));
+  print(listNode);
+  ListNode? result = listNode.reverseList(listNode);
+  print(result);
+}
+
+class ListNode {
+  int val;
+  ListNode? next;
+  ListNode([this.val = 0, this.next]);
+
+  @override
+  String toString(){
+    ListNode? cur = this;
+    String result = "";
+    while( cur!=null){
+      result = result +cur.val.toString();
+      cur = cur.next;
+      if(cur!=null){
+        result +='->';
+      }
+    }
+    return result;
+  }
+
+  ListNode? reverseList(ListNode? head) {
+    if (head == null || head.next == null) return head;
+    ListNode? pre = reverseList(head.next);
+    head.next?.next = head;
+    head.next = null;
+    return pre;
+  }
+}
+
+
+