Merge branch 'youngyangyang04:master' into remote

problems/0017.电话号码的字母组合.md

@@ -420,6 +420,40 @@ var letterCombinations = function(digits) {
 };
 ```
 
+## TypeScript
+
+```typescript
+function letterCombinations(digits: string): string[] {
+    if (digits === '') return [];
+    const strMap: { [index: string]: string[] } = {
+        1: [],
+        2: ['a', 'b', 'c'],
+        3: ['d', 'e', 'f'],
+        4: ['g', 'h', 'i'],
+        5: ['j', 'k', 'l'],
+        6: ['m', 'n', 'o'],
+        7: ['p', 'q', 'r', 's'],
+        8: ['t', 'u', 'v'],
+        9: ['w', 'x', 'y', 'z'],
+    }
+    const resArr: string[] = [];
+    function backTracking(digits: string, curIndex: number, route: string[]): void {
+        if (curIndex === digits.length) {
+            resArr.push(route.join(''));
+            return;
+        }
+        let tempArr: string[] = strMap[digits[curIndex]];
+        for (let i = 0, length = tempArr.length; i < length; i++) {
+            route.push(tempArr[i]);
+            backTracking(digits, curIndex + 1, route);
+            route.pop();
+        }
+    }
+    backTracking(digits, 0, []);
+    return resArr;
+};
+```
+
 ## C
 
 ```c

problems/0127.单词接龙.md

@@ -134,7 +134,29 @@ public int ladderLength(String beginWord, String endWord, List<String> wordList)
 ```
 
 ## Python 
-
+```
+class Solution:
+    def ladderLength(self, beginWord: str, endWord: str, wordList: List[str]) -> int:
+        wordSet = set(wordList)
+        if len(wordSet)== 0 or endWord not in wordSet:
+            return 0
+        mapping = {beginWord:1}
+        queue = deque([beginWord]) 
+        while queue:
+            word = queue.popleft()
+            path = mapping[word]
+            for i in range(len(word)):
+                word_list = list(word)
+                for j in range(26):
+                    word_list[i] = chr(ord('a')+j)
+                    newWord = "".join(word_list)
+                    if newWord == endWord:
+                        return path+1
+                    if newWord in wordSet and newWord not in mapping:
+                        mapping[newWord] = path+1
+                        queue.append(newWord)                      
+        return 0
+```
 ## Go 
 
 ## JavaScript

problems/0141.环形链表.md

@@ -106,6 +106,21 @@ class Solution:
 ## Go
 
 ```go
+func hasCycle(head *ListNode) bool {
+    if head==nil{
+        return false
+    } //空链表一定不会有环
+    fast:=head
+    slow:=head //快慢指针
+    for fast.Next!=nil&&fast.Next.Next!=nil{
+        fast=fast.Next.Next
+        slow=slow.Next
+        if fast==slow{
+            return true  //快慢指针相遇则有环
+        }
+    }
+    return false
+}
 ```
 
 ### JavaScript

problems/0189.旋转数组.md

@@ -124,6 +124,19 @@ class Solution:
 ## Go
 
 ```go
+func rotate(nums []int, k int)  {
+    l:=len(nums)
+    index:=l-k%l
+    reverse(nums)
+    reverse(nums[:l-index])
+    reverse(nums[l-index:])
+}
+func reverse(nums []int){
+    l:=len(nums)
+    for i:=0;i<l/2;i++{
+        nums[i],nums[l-1-i]=nums[l-1-i],nums[i]
+    }
+}
 ```
 
 ## JavaScript