diff --git a/problems/0020.有效的括号.md b/problems/0020.有效的括号.md
index 7bb7f746..a0df0d07 100644
--- a/problems/0020.有效的括号.md
+++ b/problems/0020.有效的括号.md
@@ -400,6 +400,27 @@ bool isValid(char * s){
return !stackTop;
}
```
-
+Scala:
+```scala
+object Solution {
+ import scala.collection.mutable
+ def isValid(s: String): Boolean = {
+ if(s.length % 2 != 0) return false // 如果字符串长度是奇数直接返回false
+ val stack = mutable.Stack[Char]()
+ // 循环遍历字符串
+ for (i <- s.indices) {
+ val c = s(i)
+ if (c == '(' || c == '[' || c == '{') stack.push(c)
+ else if(stack.isEmpty) return false // 如果没有(、[、{则直接返回false
+ // 以下三种情况，不满足则直接返回false
+ else if(c==')' && stack.pop() != '(') return false
+ else if(c==']' && stack.pop() != '[') return false
+ else if(c=='}' && stack.pop() != '{') return false
+ }
+ // 如果为空则正确匹配，否则还有余孽就不匹配
+ stack.isEmpty
+ }
+}
+```
-----------------------
diff --git a/problems/0056.合并区间.md b/problems/0056.合并区间.md
index 92b66473..e444a221 100644
--- a/problems/0056.合并区间.md
+++ b/problems/0056.合并区间.md
@@ -96,7 +96,7 @@ public:
vector> merge(vector>& intervals) {
vector> result;
if (intervals.size() == 0) return result;
- // 排序的参数使用了lamda表达式
+ // 排序的参数使用了lambda表达式
sort(intervals.begin(), intervals.end(), [](const vector& a, const vector& b){return a[0] < b[0];});
result.push_back(intervals[0]);
diff --git a/problems/0151.翻转字符串里的单词.md b/problems/0151.翻转字符串里的单词.md
index d03de421..0e25fc4d 100644
--- a/problems/0151.翻转字符串里的单词.md
+++ b/problems/0151.翻转字符串里的单词.md
@@ -758,7 +758,63 @@ func reverseWord(_ s: inout [Character]) {
}
```
+Scala:
+```scala
+object Solution {
+ def reverseWords(s: String): String = {
+ var sb = removeSpace(s) // 移除多余的空格
+ reverseString(sb, 0, sb.length - 1) // 翻转字符串
+ reverseEachWord(sb)
+ sb.mkString
+ }
+
+ // 移除多余的空格
+ def removeSpace(s: String): Array[Char] = {
+ var start = 0
+ var end = s.length - 1
+ // 移除字符串前面的空格
+ while (start < s.length && s(start) == ' ') start += 1
+ // 移除字符串后面的空格
+ while (end >= 0 && s(end) == ' ') end -= 1
+ var sb = "" // String
+ // 当start小于等于end的时候，执行添加操作
+ while (start <= end) {
+ var c = s(start)
+ // 当前字符不等于空，sb的最后一个字符不等于空的时候添加到sb
+ if (c != ' ' || sb(sb.length - 1) != ' ') {
+ sb ++= c.toString
+ }
+ start += 1 // 指针向右移动
+ }
+ sb.toArray
+ }
+
+ // 翻转字符串
+ def reverseString(s: Array[Char], start: Int, end: Int): Unit = {
+ var (left, right) = (start, end)
+ while (left < right) {
+ var tmp = s(left)
+ s(left) = s(right)
+ s(right) = tmp
+ left += 1
+ right -= 1
+ }
+ }
+
+ // 翻转每个单词
+ def reverseEachWord(s: Array[Char]): Unit = {
+ var i = 0
+ while (i < s.length) {
+ var j = i + 1
+ // 向后迭代寻找每个单词的坐标
+ while (j < s.length && s(j) != ' ') j += 1
+ reverseString(s, i, j - 1) // 翻转每个单词
+ i = j + 1 // i往后更新
+ }
+ }
+}
+```
diff --git a/problems/0203.移除链表元素.md b/problems/0203.移除链表元素.md
index 67776529..fe78ddab 100644
--- a/problems/0203.移除链表元素.md
+++ b/problems/0203.移除链表元素.md
@@ -266,6 +266,27 @@ public ListNode removeElements(ListNode head, int val) {
}
return head;
}
+/**
+ * 不添加虚拟节点and pre Node方式
+ * 时间复杂度 O(n)
+ * 空间复杂度 O(1)
+ * @param head
+ * @param val
+ * @return
+ */
+public ListNode removeElements(ListNode head, int val) {
+ while(head!=null && head.val==val){
+ head = head.next;
+ }
+ ListNode curr = head;
+ while(curr!=null){
+ while(curr.next!=null && curr.next.val == val){
+ curr.next = curr.next.next;
+ }
+ curr = curr.next;
+ }
+ return head;
+}
```
Python：
diff --git a/problems/0225.用队列实现栈.md b/problems/0225.用队列实现栈.md
index 3457c4b3..3c134870 100644
--- a/problems/0225.用队列实现栈.md
+++ b/problems/0225.用队列实现栈.md
@@ -815,6 +815,89 @@ class MyStack {
}
}
```
+Scala:
+使用两个队列模拟栈:
+```scala
+import scala.collection.mutable
+
+class MyStack() {
+
+ val queue1 = new mutable.Queue[Int]()
+ val queue2 = new mutable.Queue[Int]()
+
+ def push(x: Int) {
+ queue1.enqueue(x)
+ }
+
+ def pop(): Int = {
+ var size = queue1.size
+ // 将queue1中的每个元素都移动到queue2
+ for (i <- 0 until size - 1) {
+ queue2.enqueue(queue1.dequeue())
+ }
+ var res = queue1.dequeue()
+ // 再将queue2中的每个元素都移动到queue1
+ while (!queue2.isEmpty) {
+ queue1.enqueue(queue2.dequeue())
+ }
+ res
+ }
+
+ def top(): Int = {
+ var size = queue1.size
+ for (i <- 0 until size - 1) {
+ queue2.enqueue(queue1.dequeue())
+ }
+ var res = queue1.dequeue()
+ while (!queue2.isEmpty) {
+ queue1.enqueue(queue2.dequeue())
+ }
+ // 最终还需要把res送进queue1
+ queue1.enqueue(res)
+ res
+ }
+
+ def empty(): Boolean = {
+ queue1.isEmpty
+ }
+}
+```
+使用一个队列模拟:
+```scala
+import scala.collection.mutable
+
+class MyStack() {
+
+ val queue = new mutable.Queue[Int]()
+
+ def push(x: Int) {
+ queue.enqueue(x)
+ }
+
+ def pop(): Int = {
+ var size = queue.size
+ for (i <- 0 until size - 1) {
+ queue.enqueue(queue.head) // 把头添到队列最后
+ queue.dequeue() // 再出队
+ }
+ queue.dequeue()
+ }
+
+ def top(): Int = {
+ var size = queue.size
+ var res = 0
+ for (i <- 0 until size) {
+ queue.enqueue(queue.head) // 把头添到队列最后
+ res = queue.dequeue() // 再出队
+ }
+ res
+ }
+
+ def empty(): Boolean = {
+ queue.isEmpty
+ }
+}
+```
-----------------------
diff --git a/problems/0232.用栈实现队列.md b/problems/0232.用栈实现队列.md
index 1a56d9f3..d9ba8e26 100644
--- a/problems/0232.用栈实现队列.md
+++ b/problems/0232.用栈实现队列.md
@@ -495,6 +495,45 @@ void myQueueFree(MyQueue* obj) {
obj->stackOutTop = 0;
}
```
+Scala:
+```scala
+class MyQueue() {
+ import scala.collection.mutable
+ val stackIn = mutable.Stack[Int]() // 负责出栈
+ val stackOut = mutable.Stack[Int]() // 负责入栈
+ // 添加元素
+ def push(x: Int) {
+ stackIn.push(x)
+ }
+
+ // 复用代码，如果stackOut为空就把stackIn的所有元素都压入StackOut
+ def dumpStackIn(): Unit = {
+ if (!stackOut.isEmpty) return
+ while (!stackIn.isEmpty) {
+ stackOut.push(stackIn.pop())
+ }
+ }
+
+ // 弹出元素
+ def pop(): Int = {
+ dumpStackIn()
+ stackOut.pop()
+ }
+
+ // 获取队头
+ def peek(): Int = {
+ dumpStackIn()
+ val res: Int = stackOut.pop()
+ stackOut.push(res)
+ res
+ }
+
+ // 判断是否为空
+ def empty(): Boolean = {
+ stackIn.isEmpty && stackOut.isEmpty
+ }
+}
+```
-----------------------
diff --git a/problems/0404.左叶子之和.md b/problems/0404.左叶子之和.md
index d7fd629e..4ef68d3b 100644
--- a/problems/0404.左叶子之和.md
+++ b/problems/0404.左叶子之和.md
@@ -336,8 +336,8 @@ var sumOfLeftLeaves = function(root) {
if(node===null){
return 0;
}
- let leftValue = sumOfLeftLeaves(node.left);
- let rightValue = sumOfLeftLeaves(node.right);
+ let leftValue = nodesSum(node.left);
+ let rightValue = nodesSum(node.right);
// 3. 单层递归逻辑
let midValue = 0;
if(node.left&&node.left.left===null&&node.left.right===null){
diff --git a/problems/0516.最长回文子序列.md b/problems/0516.最长回文子序列.md
index 69536cef..63120b14 100644
--- a/problems/0516.最长回文子序列.md
+++ b/problems/0516.最长回文子序列.md
@@ -186,29 +186,28 @@ class Solution:
Go：
```Go
func longestPalindromeSubseq(s string) int {
- lenth:=len(s)
- dp:=make([][]int,lenth)
- for i:=0;i b {
+ return a
+ }
+ return b
+ }
+ dp := make([][]int, size)
+ for i := 0; i < size; i++ {
+ dp[i] = make([]int, size)
+ dp[i][i] = 1
+ }
+ for i := size - 1; i >= 0; i-- {
+ for j := i + 1; j < size; j++ {
+ if s[i] == s[j] {
+ dp[i][j] = dp[i+1][j-1] + 2
+ } else {
+ dp[i][j] = max(dp[i][j-1], dp[i+1][j])
}
}
}
- for i:=lenth-1;i>=0;i--{
- for j:=i+1;jstack=new Stack<>();
+ Deque stack=new LinkedList<>();
stack.push(0);
for(int i=1;istack=new Stack<>();
+ Deque stack=new LinkedList<>();
for(int i=0;itemperatures[stack.peek()]){
diff --git a/problems/1047.删除字符串中的所有相邻重复项.md b/problems/1047.删除字符串中的所有相邻重复项.md
index 638c8f4e..a92a3911 100644
--- a/problems/1047.删除字符串中的所有相邻重复项.md
+++ b/problems/1047.删除字符串中的所有相邻重复项.md
@@ -374,6 +374,27 @@ func removeDuplicates(_ s: String) -> String {
return String(stack)
}
```
-
+Scala:
+```scala
+object Solution {
+ import scala.collection.mutable
+ def removeDuplicates(s: String): String = {
+ var stack = mutable.Stack[Int]()
+ var str = "" // 保存最终结果
+ for (i <- s.indices) {
+ var tmp = s(i)
+ // 如果栈非空并且栈顶元素等于当前字符，那么删掉栈顶和字符串最后一个元素
+ if (!stack.isEmpty && tmp == stack.head) {
+ str = str.take(str.length - 1)
+ stack.pop()
+ } else {
+ stack.push(tmp)
+ str += tmp
+ }
+ }
+ str
+ }
+}
+```
-----------------------
diff --git a/problems/剑指Offer58-II.左旋转字符串.md b/problems/剑指Offer58-II.左旋转字符串.md
index fec83e1d..7c39ed69 100644
--- a/problems/剑指Offer58-II.左旋转字符串.md
+++ b/problems/剑指Offer58-II.左旋转字符串.md
@@ -291,6 +291,56 @@ func reverseString(_ s: inout [Character], startIndex: Int, endIndex: Int) {
```
+### PHP
+
+```php
+function reverseLeftWords($s, $n) {
+ $this->reverse($s,0,$n-1); //反转区间为前n的子串
+ $this->reverse($s,$n,strlen($s)-1); //反转区间为n到末尾的子串
+ $this->reverse($s,0,strlen($s)-1); //反转整个字符串
+ return $s;
+}
+
+// 按指定进行翻转 【array、string都可】
+function reverse(&$s, $start, $end) {
+ for ($i = $start, $j = $end; $i < $j; $i++, $j--) {
+ $tmp = $s[$i];
+ $s[$i] = $s[$j];
+ $s[$j] = $tmp;
+ }
+}
+```
+
+
+Scala:
+
+```scala
+object Solution {
+ def reverseLeftWords(s: String, n: Int): String = {
+ var str = s.toCharArray // 转换为Array
+ // abcdefg => ba cdefg
+ reverseString(str, 0, n - 1)
+ // ba cdefg => ba gfedc
+ reverseString(str, n, str.length - 1)
+ // ba gfedc => cdefgab
+ reverseString(str, 0, str.length - 1)
+ // 最终返回，return关键字可以省略
+ new String(str)
+ }
+ // 翻转字符串
+ def reverseString(s: Array[Char], start: Int, end: Int): Unit = {
+ var (left, right) = (start, end)
+ while (left < right) {
+ var tmp = s(left)
+ s(left) = s(right)
+ s(right) = tmp
+ left += 1
+ right -= 1
+ }
+ }
+}
+```
+