810

Author: lzl124631x

README.md

@@ -649,6 +649,7 @@ Now I'm using a Chrome Extension I developed -- [LeetCoder](https://chrome.googl
 806 | Number of Lines To Write String | Easy | [Solution](leetcode/806.%20Number%20of%20Lines%20To%20Write%20String)
 807 | Max Increase to Keep City Skyline | Medium | [Solution](leetcode/807.%20Max%20Increase%20to%20Keep%20City%20Skyline)
 809 | Expressive Words | Medium | [Solution](leetcode/809.%20Expressive%20Words)
+810 | Chalkboard XOR Game | Hard | [Solution](leetcode/810.%20Chalkboard%20XOR%20Game)
 811 | Subdomain Visit Count | Easy | [Solution](leetcode/811.%20Subdomain%20Visit%20Count)
 812 | Largest Triangle Area | Easy | [Solution](leetcode/812.%20Largest%20Triangle%20Area)
 813 | Largest Sum of Averages | Medium | [Solution](leetcode/813.%20Largest%20Sum%20of%20Averages)
@@ -1281,6 +1282,10 @@ Now I'm using a Chrome Extension I developed -- [LeetCoder](https://chrome.googl
 1797 | Design Authentication Manager | Medium | [Solution](leetcode/1797.%20Design%20Authentication%20Manager)
 1798 | Maximum Number of Consecutive Values You Can Make | Medium | [Solution](leetcode/1798.%20Maximum%20Number%20of%20Consecutive%20Values%20You%20Can%20Make)
 1799 | Maximize Score After N Operations | Hard | [Solution](leetcode/1799.%20Maximize%20Score%20After%20N%20Operations)
+1800 | Maximum Ascending Subarray Sum | Easy | [Solution](leetcode/1800.%20Maximum%20Ascending%20Subarray%20Sum)
+1801 | Number of Orders in the Backlog | Medium | [Solution](leetcode/1801.%20Number%20of%20Orders%20in%20the%20Backlog)
+1802 | Maximum Value at a Given Index in a Bounded Array | Medium | [Solution](leetcode/1802.%20Maximum%20Value%20at%20a%20Given%20Index%20in%20a%20Bounded%20Array)
+1803 | Count Pairs With XOR in a Range | Hard | [Solution](leetcode/1803.%20Count%20Pairs%20With%20XOR%20in%20a%20Range)
 
 # License
 

leetcode/810. Chalkboard XOR Game/README.md

@@ -0,0 +1,47 @@
+# [810. Chalkboard XOR Game (Hard)](https://leetcode.com/problems/chalkboard-xor-game/)
+
+<p>We are given non-negative integers nums[i] which are written on a chalkboard.&nbsp; Alice and Bob take turns erasing exactly one number from the chalkboard, with Alice starting first.&nbsp; If erasing a number causes&nbsp;the bitwise XOR of all the elements of the chalkboard to become&nbsp;0, then that player loses.&nbsp; (Also, we'll say the bitwise XOR of one element is that element itself, and the bitwise XOR of no elements is 0.)</p>
+
+<p>Also, if any player starts their turn with the bitwise XOR of all the elements of the chalkboard equal to 0, then that player wins.</p>
+
+<p>Return True if and only if Alice wins the game, assuming both players play optimally.</p>
+
+<pre><strong>Example:</strong>
+<strong>Input:</strong> nums = [1, 1, 2]
+<strong>Output:</strong> false
+<strong>Explanation:</strong> 
+Alice has two choices: erase 1 or erase 2. 
+If she erases 1, the nums array becomes [1, 2]. The bitwise XOR of all the elements of the chalkboard is 1 XOR 2 = 3. Now Bob can remove any element he wants, because Alice will be the one to erase the last element and she will lose. 
+If Alice erases 2 first, now nums becomes [1, 1]. The bitwise XOR of all the elements of the chalkboard is 1 XOR 1 = 0. Alice will lose.
+
+</pre>
+
+<p><strong>Notes: </strong></p>
+
+<ul>
+	<li><code>1 &lt;= N &lt;= 1000</code>.&nbsp;</li>
+	<li><code>0 &lt;= nums[i] &lt;= 2^16</code>.</li>
+</ul>
+
+<p>&nbsp;</p>
+
+
+**Related Topics**:  
+[Math](https://leetcode.com/tag/math/)
+
+## Solution 1.
+
+```cpp
+// OJ: https://leetcode.com/problems/chalkboard-xor-game/
+// Author: github.com/lzl124631x
+// Time: O(N)
+// Space: O(1)
+class Solution {
+public:
+    bool xorGame(vector<int>& A) {
+        int x = 0;
+        for (int n : A) x ^= n;
+        return A.size() % 2 == 0 || x == 0;
+    }
+};
+```