feat: add solutions to lc problem: No.1720. Decode XORed Array

Author: yanglbme

solution/1700-1799/1720.Decode XORed Array/README.md

@@ -42,27 +42,45 @@
 	<li><code>0 <= first <= 10<sup>5</sup></code></li>
 </ul>
 
-
 ## 解法
 
 <!-- 这里可写通用的实现逻辑 -->
 
+异或运算。
+
+`a = b ^ c` => `a ^ b = b ^ c ^ b` => `c = a ^ b`。
+
 <!-- tabs:start -->
 
 ### **Python3**
 
 <!-- 这里可写当前语言的特殊实现逻辑 -->
 
 ```python
-
+class Solution:
+    def decode(self, encoded: List[int], first: int) -> List[int]:
+        res = [first]
+        for e in encoded:
+            first ^= e
+            res.append(first)
+        return res
 ```
 
 ### **Java**
 
 <!-- 这里可写当前语言的特殊实现逻辑 -->
 
 ```java
-
+class Solution {
+    public int[] decode(int[] encoded, int first) {
+        int[] res = new int[encoded.length + 1];
+        res[0] = first;
+        for (int i = 0; i < encoded.length; ++i) {
+            res[i + 1] = res[i] ^ encoded[i];
+        }
+        return res;
+    }
+}
 ```
 
 ### **...**

solution/1700-1799/1720.Decode XORed Array/README_EN.md

@@ -38,21 +38,39 @@
 	<li><code>0 &lt;= first &lt;= 10<sup>5</sup></code></li>
 </ul>
 
-
 ## Solutions
 
+XOR.
+
+`a = b ^ c` => `a ^ b = b ^ c ^ b` => `c = a ^ b`.
+
 <!-- tabs:start -->
 
 ### **Python3**
 
 ```python
-
+class Solution:
+    def decode(self, encoded: List[int], first: int) -> List[int]:
+        res = [first]
+        for e in encoded:
+            first ^= e
+            res.append(first)
+        return res
 ```
 
 ### **Java**
 
 ```java
-
+class Solution {
+    public int[] decode(int[] encoded, int first) {
+        int[] res = new int[encoded.length + 1];
+        res[0] = first;
+        for (int i = 0; i < encoded.length; ++i) {
+            res[i + 1] = res[i] ^ encoded[i];
+        }
+        return res;
+    }
+}
 ```
 
 ### **...**

solution/1700-1799/1720.Decode XORed Array/Solution.java

@@ -0,0 +1,10 @@
+class Solution {
+    public int[] decode(int[] encoded, int first) {
+        int[] res = new int[encoded.length + 1];
+        res[0] = first;
+        for (int i = 0; i < encoded.length; ++i) {
+            res[i + 1] = res[i] ^ encoded[i];
+        }
+        return res;
+    }
+}

solution/1700-1799/1720.Decode XORed Array/Solution.py

@@ -0,0 +1,7 @@
+class Solution:
+    def decode(self, encoded: List[int], first: int) -> List[int]:
+        res = [first]
+        for e in encoded:
+            first ^= e
+            res.append(first)
+        return res