Merge pull request #1602 from zhicheng-lee/master

更新 0332.重新安排行程 0051.N皇后 0077.组合优化

problems/0051.N皇后.md

@@ -222,56 +222,6 @@ public:
 
 ## 其他语言补充
 
-
-### Python 
-
-```python
-class Solution:
-    def solveNQueens(self, n: int) -> List[List[str]]:
-        if not n: return []
-        board = [['.'] * n for _ in range(n)]
-        res = []
-        def isVaild(board,row, col):
-            #判断同一列是否冲突
-            for i in range(len(board)):
-                if board[i][col] == 'Q':
-                    return False
-            # 判断左上角是否冲突
-            i = row -1
-            j = col -1
-            while i>=0 and j>=0:
-                if board[i][j] == 'Q':
-                    return False
-                i -= 1
-                j -= 1
-            # 判断右上角是否冲突
-            i = row - 1
-            j = col + 1
-            while i>=0 and j < len(board):
-                if board[i][j] == 'Q':
-                    return False
-                i -= 1
-                j += 1
-            return True
-
-        def backtracking(board, row, n):
-            # 如果走到最后一行，说明已经找到一个解
-            if row == n:
-                temp_res = []
-                for temp in board:
-                    temp_str = "".join(temp)
-                    temp_res.append(temp_str)
-                res.append(temp_res)
-            for col in range(n):
-                if not isVaild(board, row, col):
-                    continue
-                board[row][col] = 'Q'
-                backtracking(board, row+1, n)
-                board[row][col] = '.'
-        backtracking(board, 0, n)
-        return res
-```
-
 ### Java 
 
 ```java
@@ -341,6 +291,55 @@ class Solution {
 }
 ```
 
+### Python 
+
+```python
+class Solution:
+    def solveNQueens(self, n: int) -> List[List[str]]:
+        if not n: return []
+        board = [['.'] * n for _ in range(n)]
+        res = []
+        def isVaild(board,row, col):
+            #判断同一列是否冲突
+            for i in range(len(board)):
+                if board[i][col] == 'Q':
+                    return False
+            # 判断左上角是否冲突
+            i = row -1
+            j = col -1
+            while i>=0 and j>=0:
+                if board[i][j] == 'Q':
+                    return False
+                i -= 1
+                j -= 1
+            # 判断右上角是否冲突
+            i = row - 1
+            j = col + 1
+            while i>=0 and j < len(board):
+                if board[i][j] == 'Q':
+                    return False
+                i -= 1
+                j += 1
+            return True
+
+        def backtracking(board, row, n):
+            # 如果走到最后一行，说明已经找到一个解
+            if row == n:
+                temp_res = []
+                for temp in board:
+                    temp_str = "".join(temp)
+                    temp_res.append(temp_str)
+                res.append(temp_res)
+            for col in range(n):
+                if not isVaild(board, row, col):
+                    continue
+                board[row][col] = 'Q'
+                backtracking(board, row+1, n)
+                board[row][col] = '.'
+        backtracking(board, 0, n)
+        return res
+```
+
 
 ### Go 
 ```Go
@@ -396,6 +395,8 @@ func isValid(n, row, col int, chessboard [][]string) bool {
 	return true
 }
 ```
+
+
 ### Javascript 
 ```Javascript
 var solveNQueens = function(n) {

problems/0077.组合优化.md

@@ -20,7 +20,7 @@
 
 大家先回忆一下[77. 组合]给出的回溯法的代码：
 
-```c++
+```CPP
 class Solution {
 private:
     vector<vector<int>> result; // 存放符合条件结果的集合
@@ -52,7 +52,7 @@ public:
 
 在遍历的过程中有如下代码：
 
-```c++
+```CPP
 for (int i = startIndex; i <= n; i++) {
     path.push_back(i);
     backtracking(n, k, i + 1);
@@ -76,7 +76,7 @@ for (int i = startIndex; i <= n; i++) {
 **如果for循环选择的起始位置之后的元素个数 已经不足 我们需要的元素个数了，那么就没有必要搜索了**。
 
 注意代码中i，就是for循环里选择的起始位置。
-```c++
+```CPP
 for (int i = startIndex; i <= n; i++) {
 ```
 
@@ -98,13 +98,13 @@ for (int i = startIndex; i <= n; i++) {
 
 所以优化之后的for循环是：
 
-```c++
+```CPP
 for (int i = startIndex; i <= n - (k - path.size()) + 1; i++) // i为本次搜索的起始位置
 ```
 
 优化后整体代码如下：
 
-```c++
+```CPP
 class Solution {
 private:
     vector<vector<int>> result;

problems/0332.重新安排行程.md

@@ -262,6 +262,43 @@ for (pair<string, int>target : targets[result[result.size() - 1]])
 
 ### java 
 	
+```java
+class Solution {
+    private LinkedList<String> res;
+    private LinkedList<String> path = new LinkedList<>();
+
+    public List<String> findItinerary(List<List<String>> tickets) {
+        Collections.sort(tickets, (a, b) -> a.get(1).compareTo(b.get(1)));
+        path.add("JFK");
+        boolean[] used = new boolean[tickets.size()];
+        backTracking((ArrayList) tickets, used);
+        return res;
+    }
+
+    public boolean backTracking(ArrayList<List<String>> tickets, boolean[] used) {
+        if (path.size() == tickets.size() + 1) {
+            res = new LinkedList(path);
+            return true;
+        }
+
+        for (int i = 0; i < tickets.size(); i++) {
+            if (!used[i] && tickets.get(i).get(0).equals(path.getLast())) {
+                path.add(tickets.get(i).get(1));
+                used[i] = true;
+
+                if (backTracking(tickets, used)) {
+                    return true;
+                }
+
+                used[i] = false;
+                path.removeLast();
+            }
+        }
+        return false;
+    }
+}
+```
+
 ```java
 class Solution {
     private Deque<String> res;