Merge branch 'master' of github.com:youngyangyang04/leetcode-master

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/0077.组合优化.md

@@ -240,7 +240,29 @@ var combine = function(n, k) {
 };
 ```
 
+TypeScript：
+
+```typescript
+function combine(n: number, k: number): number[][] {
+    let resArr: number[][] = [];
+    function backTracking(n: number, k: number, startIndex: number, tempArr: number[]): void {
+        if (tempArr.length === k) {
+            resArr.push(tempArr.slice());
+            return;
+        }
+        for (let i = startIndex; i <= n - k + 1 + tempArr.length; i++) {
+            tempArr.push(i);
+            backTracking(n, k, i + 1, tempArr);
+            tempArr.pop();
+        }
+    }
+    backTracking(n, k, 1, []);
+    return resArr;
+};
+```
+
 C:
+
 ```c
 int* path;
 int pathTop;

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/0134.加油站.md

@@ -239,6 +239,30 @@ class Solution {
 
 ### Python 
 ```python
+# 解法1
+class Solution:
+    def canCompleteCircuit(self, gas: List[int], cost: List[int]) -> int:
+        n = len(gas)
+        cur_sum = 0
+        min_sum = float('inf')
+        
+        for i in range(n):
+            cur_sum += gas[i] - cost[i]
+            min_sum = min(min_sum, cur_sum)
+        
+        if cur_sum < 0: return -1
+        if min_sum >= 0: return 0
+        
+        for j in range(n - 1, 0, -1):
+            min_sum += gas[j] - cost[j]
+            if min_sum >= 0:
+                return j
+        
+        return -1
+```
+
+```python
+# 解法2
 class Solution:
     def canCompleteCircuit(self, gas: List[int], cost: List[int]) -> int:
         start = 0

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/0151.翻转字符串里的单词.md

@@ -222,7 +222,44 @@ public:
 效率：
 <img src='https://code-thinking.cdn.bcebos.com/pics/151_翻转字符串里的单词.png' width=600> </img></div>
 
+```CPP
+//版本二：
+//原理同版本1，更简洁实现。
+class Solution {
+public:
+    void reverse(string& s, int start, int end){ //翻转，区间写法：闭区间 []
+        for (int i = start, j = end; i < j; i++, j--) {
+            swap(s[i], s[j]);
+        }
+    }
 
+    void removeExtraSpaces(string& s) {//去除所有空格并在相邻单词之间添加空格, 快慢指针。
+        int slow = 0;   //整体思想参考Leetcode: 27. 移除元素：https://leetcode-cn.com/problems/remove-element/
+        for (int i = 0; i < s.size(); ++i) { //
+            if (s[i] != ' ') { //遇到非空格就处理，即删除所有空格。
+                if (slow != 0) s[slow++] = ' '; //手动控制空格，给单词之间添加空格。slow != 0说明不是第一个单词，需要在单词前添加空格。
+                while (i < s.size() && s[i] != ' ') { //补上该单词，遇到空格说明单词结束。
+                    s[slow++] = s[i++];
+                }
+            }
+        }
+        s.resize(slow); //slow的大小即为去除多余空格后的大小。
+    }
+
+    string reverseWords(string s) {
+        removeExtraSpaces(s); //去除多余空格，保证单词之间之只有一个空格，且字符串首尾没空格。
+        reverse(s, 0, s.size() - 1);
+        int start = 0; //removeExtraSpaces后保证第一个单词的开始下标一定是0。
+        for (int i = 0; i <= s.size(); ++i) {
+            if (i == s.size() || s[i] == ' ') { //到达空格或者串尾，说明一个单词结束。进行翻转。
+                reverse(s, start, i - 1); //翻转，注意是左闭右闭 []的翻转。
+                start = i + 1; //更新下一个单词的开始下标start
+            }
+        }
+        return s;
+    }
+};
+```
 
 ## 其他语言版本
 

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

problems/0216.组合总和III.md

@@ -396,6 +396,30 @@ var combinationSum3 = function(k, n) {
 };
 ```
 
+## TypeScript
+
+```typescript
+function combinationSum3(k: number, n: number): number[][] {
+    const resArr: number[][] = [];
+    function backTracking(k: number, n: number, sum: number, startIndex: number, tempArr: number[]): void {
+        if (sum > n) return;
+        if (tempArr.length === k) {
+            if (sum === n) {
+                resArr.push(tempArr.slice());
+            }
+            return;
+        }
+        for (let i = startIndex; i <= 9 - (k - tempArr.length) + 1; i++) {
+            tempArr.push(i);
+            backTracking(k, n, sum + i, i + 1, tempArr);
+            tempArr.pop();
+        }
+    }
+    backTracking(k, n, 0, 1, []);
+    return resArr;
+};
+```
+
 ## C
 
 ```c

problems/0332.重新安排行程.md

@@ -342,6 +342,64 @@ class Solution:
         return path
 ```
 
+### Go
+```go
+type pair struct {
+	target  string
+	visited bool
+}
+type pairs []*pair
+
+func (p pairs) Len() int {
+	return len(p)
+}
+func (p pairs) Swap(i, j int) {
+	p[i], p[j] = p[j], p[i]
+}
+func (p pairs) Less(i, j int) bool {
+	return p[i].target < p[j].target
+}
+
+func findItinerary(tickets [][]string) []string {
+	result := []string{}
+	// map[出发机场] pair{目的地,是否被访问过}
+	targets := make(map[string]pairs)
+	for _, ticket := range tickets {
+		if targets[ticket[0]] == nil {
+			targets[ticket[0]] = make(pairs, 0)
+		}
+		targets[ticket[0]] = append(targets[ticket[0]], &pair{target: ticket[1], visited: false})
+	}
+	for k, _ := range targets {
+		sort.Sort(targets[k])
+	}
+	result = append(result, "JFK")
+	var backtracking func() bool
+	backtracking = func() bool {
+		if len(tickets)+1 == len(result) {
+			return true
+		}
+		// 取出起飞航班对应的目的地
+		for _, pair := range targets[result[len(result)-1]] {
+			if pair.visited == false {
+				result = append(result, pair.target)
+				pair.visited = true
+				if backtracking() {
+					return true
+				}
+				result = result[:len(result)-1]
+				pair.visited = false
+			}
+		}
+		return false
+	}
+
+	backtracking()
+
+	return result
+}
+```
+
 ### C语言 
 
 ```C