diff --git a/problems/0093.复原IP地址.md b/problems/0093.复原IP地址.md index 41940487..11ca2d03 100644 --- a/problems/0093.复原IP地址.md +++ b/problems/0093.复原IP地址.md @@ -659,6 +659,48 @@ func restoreIpAddresses(_ s: String) -> [String] { } ``` +## Scala + +```scala +object Solution { + import scala.collection.mutable + def restoreIpAddresses(s: String): List[String] = { + var result = mutable.ListBuffer[String]() + if (s.size < 4 || s.length > 12) return result.toList + var path = mutable.ListBuffer[String]() + + // 判断IP中的一个字段是否为正确的 + def isIP(sub: String): Boolean = { + if (sub.size > 1 && sub(0) == '0') return false + if (sub.toInt > 255) return false + true + } + + def backtracking(startIndex: Int): Unit = { + if (startIndex >= s.size) { + if (path.size == 4) { + result.append(path.mkString(".")) // mkString方法可以把集合里的数据以指定字符串拼接 + return + } + return + } + // subString + for (i <- startIndex until startIndex + 3 if i < s.size) { + var subString = s.substring(startIndex, i + 1) + if (isIP(subString)) { // 如果合法则进行下一轮 + path.append(subString) + backtracking(i + 1) + path = path.take(path.size - 1) + } + } + } + + backtracking(0) + result.toList + } +} +``` + -----------------------
diff --git a/problems/0131.分割回文串.md b/problems/0131.分割回文串.md index a371864d..64d45853 100644 --- a/problems/0131.分割回文串.md +++ b/problems/0131.分割回文串.md @@ -676,5 +676,50 @@ impl Solution { } } ``` + + +## Scala + +```scala +object Solution { + + import scala.collection.mutable + + def partition(s: String): List[List[String]] = { + var result = mutable.ListBuffer[List[String]]() + var path = mutable.ListBuffer[String]() + + // 判断字符串是否回文 + def isPalindrome(start: Int, end: Int): Boolean = { + var (left, right) = (start, end) + while (left < right) { + if (s(left) != s(right)) return false + left += 1 + right -= 1 + } + true + } + + // 回溯算法 + def backtracking(startIndex: Int): Unit = { + if (startIndex >= s.size) { + result.append(path.toList) + return + } + // 添加循环守卫,如果当前分割是回文子串则进入回溯 + for (i <- startIndex until s.size if isPalindrome(startIndex, i)) { + path.append(s.substring(startIndex, i + 1)) + backtracking(i + 1) + path = path.take(path.size - 1) + } + } + + backtracking(0) + result.toList + } +} +``` + + -----------------------
diff --git a/problems/0141.环形链表.md b/problems/0141.环形链表.md index ddd83c94..ce90b6c4 100644 --- a/problems/0141.环形链表.md +++ b/problems/0141.环形链表.md @@ -7,6 +7,8 @@ # 141. 环形链表 +[力扣题目链接](https://leetcode.cn/problems/linked-list-cycle/submissions/) + 给定一个链表,判断链表中是否有环。 如果链表中有某个节点,可以通过连续跟踪 next 指针再次到达,则链表中存在环。 为了表示给定链表中的环,我们使用整数 pos 来表示链表尾连接到链表中的位置(索引从 0 开始)。 如果 pos 是 -1,则在该链表中没有环。注意:pos 不作为参数进行传递,仅仅是为了标识链表的实际情况。 @@ -103,7 +105,7 @@ class Solution: return False ``` -## Go +### Go ```go func hasCycle(head *ListNode) bool { @@ -139,6 +141,23 @@ var hasCycle = function(head) { }; ``` +### TypeScript + +```typescript +function hasCycle(head: ListNode | null): boolean { + let slowNode: ListNode | null = head, + fastNode: ListNode | null = head; + while (fastNode !== null && fastNode.next !== null) { + slowNode = slowNode!.next; + fastNode = fastNode.next.next; + if (slowNode === fastNode) return true; + } + return false; +}; +``` + + + -----------------------
diff --git a/problems/0142.环形链表II.md b/problems/0142.环形链表II.md index 6b7c7e66..658bd868 100644 --- a/problems/0142.环形链表II.md +++ b/problems/0142.环形链表II.md @@ -301,13 +301,13 @@ function detectCycle(head: ListNode | null): ListNode | null { let slowNode: ListNode | null = head, fastNode: ListNode | null = head; while (fastNode !== null && fastNode.next !== null) { - slowNode = (slowNode as ListNode).next; + slowNode = slowNode!.next; fastNode = fastNode.next.next; if (slowNode === fastNode) { slowNode = head; while (slowNode !== fastNode) { - slowNode = (slowNode as ListNode).next; - fastNode = (fastNode as ListNode).next; + slowNode = slowNode!.next; + fastNode = fastNode!.next; } return slowNode; } diff --git a/problems/0143.重排链表.md b/problems/0143.重排链表.md index 790bcb48..c60fc0f9 100644 --- a/problems/0143.重排链表.md +++ b/problems/0143.重排链表.md @@ -6,6 +6,8 @@ # 143.重排链表 +[力扣题目链接](https://leetcode.cn/problems/reorder-list/submissions/) + ![](https://code-thinking-1253855093.file.myqcloud.com/pics/20210726160122.png) ## 思路 @@ -465,7 +467,81 @@ var reorderList = function(head, s = [], tmp) { } ``` +### TypeScript + +> 辅助数组法: + +```typescript +function reorderList(head: ListNode | null): void { + if (head === null) return; + const helperArr: ListNode[] = []; + let curNode: ListNode | null = head; + while (curNode !== null) { + helperArr.push(curNode); + curNode = curNode.next; + } + let node: ListNode = head; + let left: number = 1, + right: number = helperArr.length - 1; + let count: number = 0; + while (left <= right) { + if (count % 2 === 0) { + node.next = helperArr[right--]; + } else { + node.next = helperArr[left++]; + } + count++; + node = node.next; + } + node.next = null; +}; +``` + +> 分割链表法: + +```typescript +function reorderList(head: ListNode | null): void { + if (head === null || head.next === null) return; + let fastNode: ListNode = head, + slowNode: ListNode = head; + while (fastNode.next !== null && fastNode.next.next !== null) { + slowNode = slowNode.next!; + fastNode = fastNode.next.next; + } + let head1: ListNode | null = head; + // 反转后半部分链表 + let head2: ListNode | null = reverseList(slowNode.next); + // 分割链表 + slowNode.next = null; + /** + 直接在head1链表上进行插入 + head1 链表长度一定大于或等于head2, + 因此在下面的循环中,只要head2不为null, head1 一定不为null + */ + while (head2 !== null) { + const tempNode1: ListNode | null = head1!.next, + tempNode2: ListNode | null = head2.next; + head1!.next = head2; + head2.next = tempNode1; + head1 = tempNode1; + head2 = tempNode2; + } +}; +function reverseList(head: ListNode | null): ListNode | null { + let curNode: ListNode | null = head, + preNode: ListNode | null = null; + while (curNode !== null) { + const tempNode: ListNode | null = curNode.next; + curNode.next = preNode; + preNode = curNode; + curNode = tempNode; + } + return preNode; +} +``` + ### C + 方法三:反转链表 ```c //翻转链表