deploy: 4a32c1c

Author: yanglbme

en/lc/1524/index.html

@@ -40989,9 +40989,9 @@
       <ul class="md-nav__list">
 
           <li class="md-nav__item">
-  <a href="#solution-1" class="md-nav__link">
+  <a href="#solution-1-prefix-sum-counter" class="md-nav__link">
     <span class="md-ellipsis">
-      Solution 1
+      Solution 1: Prefix Sum + Counter
     </span>
   </a>
 
@@ -86563,8 +86563,13 @@ <h2 id="description">Description</h2>
 <h2 id="solutions">Solutions</h2>
 <!-- solution:start -->
 
-<h3 id="solution-1">Solution 1</h3>
-<div class="tabbed-set tabbed-alternate" data-tabs="1:5"><input checked="checked" id="__tabbed_1_1" name="__tabbed_1" type="radio" /><input id="__tabbed_1_2" name="__tabbed_1" type="radio" /><input id="__tabbed_1_3" name="__tabbed_1" type="radio" /><input id="__tabbed_1_4" name="__tabbed_1" type="radio" /><input id="__tabbed_1_5" name="__tabbed_1" type="radio" /><div class="tabbed-labels"><label for="__tabbed_1_1">Python3</label><label for="__tabbed_1_2">Java</label><label for="__tabbed_1_3">C++</label><label for="__tabbed_1_4">Go</label><label for="__tabbed_1_5">TypeScript</label></div>
+<h3 id="solution-1-prefix-sum-counter">Solution 1: Prefix Sum + Counter</h3>
+<p>We define an array <span class="arithmatex">\(\textit{cnt}\)</span> of length 2 as a counter, where <span class="arithmatex">\(\textit{cnt}[0]\)</span> and <span class="arithmatex">\(\textit{cnt}[1]\)</span> represent the number of subarrays with even and odd prefix sums, respectively. Initially, <span class="arithmatex">\(\textit{cnt}[0] = 1\)</span> and <span class="arithmatex">\(\textit{cnt}[1] = 0\)</span>.</p>
+<p>Next, we maintain the current prefix sum <span class="arithmatex">\(s\)</span>, initially <span class="arithmatex">\(s = 0\)</span>.</p>
+<p>Traverse the array <span class="arithmatex">\(\textit{arr}\)</span>, for each element <span class="arithmatex">\(x\)</span> encountered, add the value of <span class="arithmatex">\(x\)</span> to <span class="arithmatex">\(s\)</span>, then based on the parity of <span class="arithmatex">\(s\)</span>, add the value of <span class="arithmatex">\(\textit{cnt}[s \mod 2 \oplus 1]\)</span> to the answer, and then increment the value of <span class="arithmatex">\(\textit{cnt}[s \mod 2]\)</span> by 1.</p>
+<p>After the traversal, we get the answer. Note the modulo operation for the answer.</p>
+<p>Time complexity is <span class="arithmatex">\(O(n)\)</span>, where <span class="arithmatex">\(n\)</span> is the length of the array <span class="arithmatex">\(\textit{arr}\)</span>. Space complexity is <span class="arithmatex">\(O(1)\)</span>.</p>
+<div class="tabbed-set tabbed-alternate" data-tabs="1:6"><input checked="checked" id="__tabbed_1_1" name="__tabbed_1" type="radio" /><input id="__tabbed_1_2" name="__tabbed_1" type="radio" /><input id="__tabbed_1_3" name="__tabbed_1" type="radio" /><input id="__tabbed_1_4" name="__tabbed_1" type="radio" /><input id="__tabbed_1_5" name="__tabbed_1" type="radio" /><input id="__tabbed_1_6" name="__tabbed_1" type="radio" /><div class="tabbed-labels"><label for="__tabbed_1_1">Python3</label><label for="__tabbed_1_2">Java</label><label for="__tabbed_1_3">C++</label><label for="__tabbed_1_4">Go</label><label for="__tabbed_1_5">TypeScript</label><label for="__tabbed_1_6">Rust</label></div>
 <div class="tabbed-content">
 <div class="tabbed-block">
 <div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span></span><span class="normal"> 1</span>
@@ -86696,6 +86701,36 @@ <h3 id="solution-1">Solution 1</h3>
 <span class="p">}</span>
 </code></pre></div></td></tr></table></div>
 </div>
+<div class="tabbed-block">
+<div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span></span><span class="normal"> 1</span>
+<span class="normal"> 2</span>
+<span class="normal"> 3</span>
+<span class="normal"> 4</span>
+<span class="normal"> 5</span>
+<span class="normal"> 6</span>
+<span class="normal"> 7</span>
+<span class="normal"> 8</span>
+<span class="normal"> 9</span>
+<span class="normal">10</span>
+<span class="normal">11</span>
+<span class="normal">12</span>
+<span class="normal">13</span>
+<span class="normal">14</span></pre></div></td><td class="code"><div><pre><span></span><code><span class="k">impl</span><span class="w"> </span><span class="n">Solution</span><span class="w"> </span><span class="p">{</span>
+<span class="w">    </span><span class="k">pub</span><span class="w"> </span><span class="k">fn</span><span class="w"> </span><span class="nf">num_of_subarrays</span><span class="p">(</span><span class="n">arr</span><span class="p">:</span><span class="w"> </span><span class="nb">Vec</span><span class="o">&lt;</span><span class="kt">i32</span><span class="o">&gt;</span><span class="p">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="kt">i32</span><span class="w"> </span><span class="p">{</span>
+<span class="w">        </span><span class="k">const</span><span class="w"> </span><span class="n">MOD</span><span class="p">:</span><span class="w"> </span><span class="kt">i32</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mi">1_000_000_007</span><span class="p">;</span>
+<span class="w">        </span><span class="kd">let</span><span class="w"> </span><span class="k">mut</span><span class="w"> </span><span class="n">cnt</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p">[</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="mi">0</span><span class="p">];</span>
+<span class="w">        </span><span class="kd">let</span><span class="w"> </span><span class="k">mut</span><span class="w"> </span><span class="n">ans</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mi">0</span><span class="p">;</span>
+<span class="w">        </span><span class="kd">let</span><span class="w"> </span><span class="k">mut</span><span class="w"> </span><span class="n">s</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mi">0</span><span class="p">;</span>
+<span class="w">        </span><span class="k">for</span><span class="w"> </span><span class="o">&amp;</span><span class="n">x</span><span class="w"> </span><span class="k">in</span><span class="w"> </span><span class="n">arr</span><span class="p">.</span><span class="n">iter</span><span class="p">()</span><span class="w"> </span><span class="p">{</span>
+<span class="w">            </span><span class="n">s</span><span class="w"> </span><span class="o">+=</span><span class="w"> </span><span class="n">x</span><span class="p">;</span>
+<span class="w">            </span><span class="n">ans</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p">(</span><span class="n">ans</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">cnt</span><span class="p">[((</span><span class="n">s</span><span class="w"> </span><span class="o">&amp;</span><span class="w"> </span><span class="mi">1</span><span class="p">)</span><span class="w"> </span><span class="o">^</span><span class="w"> </span><span class="mi">1</span><span class="p">)</span><span class="w"> </span><span class="k">as</span><span class="w"> </span><span class="kt">usize</span><span class="p">])</span><span class="w"> </span><span class="o">%</span><span class="w"> </span><span class="n">MOD</span><span class="p">;</span>
+<span class="w">            </span><span class="n">cnt</span><span class="p">[(</span><span class="n">s</span><span class="w"> </span><span class="o">&amp;</span><span class="w"> </span><span class="mi">1</span><span class="p">)</span><span class="w"> </span><span class="k">as</span><span class="w"> </span><span class="kt">usize</span><span class="p">]</span><span class="w"> </span><span class="o">+=</span><span class="w"> </span><span class="mi">1</span><span class="p">;</span>
+<span class="w">        </span><span class="p">}</span>
+<span class="w">        </span><span class="n">ans</span>
+<span class="w">    </span><span class="p">}</span>
+<span class="p">}</span>
+</code></pre></div></td></tr></table></div>
+</div>
 </div>
 </div>
 <!-- solution:end -->

en/search/search_index.json

@@ -91371,12 +91371,12 @@ <h2 id="_2">解法</h2>
 <!-- solution:start -->
 
 <h3 id="_3">方法一：前缀和 + 计数器</h3>
-<p>我们定义一个长度为 <span class="arithmatex">\(2\)</span> 的数组 <span class="arithmatex">\(cnt\)</span> 作为计数器，其中 <span class="arithmatex">\(cnt[0]\)</span> 和 <span class="arithmatex">\(cnt[1]\)</span> 分别表示前缀和为偶数和奇数的子数组的个数。初始时 <span class="arithmatex">\(cnt[0] = 1\)</span>，而 <span class="arithmatex">\(cnt[1] = 0\)</span>。</p>
+<p>我们定义一个长度为 <span class="arithmatex">\(2\)</span> 的数组 <span class="arithmatex">\(\textit{cnt}\)</span> 作为计数器，其中 <span class="arithmatex">\(\textit{cnt}[0]\)</span> 和 <span class="arithmatex">\(\textit{cnt}[1]\)</span> 分别表示前缀和为偶数和奇数的子数组的个数。初始时 <span class="arithmatex">\(\textit{cnt}[0] = 1\)</span>，而 <span class="arithmatex">\(\textit{cnt}[1] = 0\)</span>。</p>
 <p>接下来，我们维护当前的前缀和 <span class="arithmatex">\(s\)</span>，初始时 <span class="arithmatex">\(s = 0\)</span>。</p>
-<p>遍历数组 <span class="arithmatex">\(arr\)</span>，对于遍历到的每个元素 <span class="arithmatex">\(x\)</span>，我们将 <span class="arithmatex">\(s\)</span> 的值加上 <span class="arithmatex">\(x\)</span>，然后根据 <span class="arithmatex">\(s\)</span> 的奇偶性，将 <span class="arithmatex">\(cnt[s \mod 2 \oplus 1]\)</span> 的值累加到答案中，然后我们将 <span class="arithmatex">\(cnt[s \mod 2]\)</span> 的值加 <span class="arithmatex">\(1\)</span>。</p>
+<p>遍历数组 <span class="arithmatex">\(\textit{arr}\)</span>，对于遍历到的每个元素 <span class="arithmatex">\(x\)</span>，我们将 <span class="arithmatex">\(s\)</span> 的值加上 <span class="arithmatex">\(x\)</span>，然后根据 <span class="arithmatex">\(s\)</span> 的奇偶性，将 <span class="arithmatex">\(\textit{cnt}[s \mod 2 \oplus 1]\)</span> 的值累加到答案中，然后我们将 <span class="arithmatex">\(\textit{cnt}[s \mod 2]\)</span> 的值加 <span class="arithmatex">\(1\)</span>。</p>
 <p>遍历结束后，我们即可得到答案。注意答案的取模运算。</p>
-<p>时间复杂度 <span class="arithmatex">\(O(n)\)</span>，空间复杂度 <span class="arithmatex">\(O(1)\)</span>。其中 <span class="arithmatex">\(n\)</span> 为数组 <span class="arithmatex">\(arr\)</span> 的长度。</p>
-<div class="tabbed-set tabbed-alternate" data-tabs="1:5"><input checked="checked" id="__tabbed_1_1" name="__tabbed_1" type="radio" /><input id="__tabbed_1_2" name="__tabbed_1" type="radio" /><input id="__tabbed_1_3" name="__tabbed_1" type="radio" /><input id="__tabbed_1_4" name="__tabbed_1" type="radio" /><input id="__tabbed_1_5" name="__tabbed_1" type="radio" /><div class="tabbed-labels"><label for="__tabbed_1_1">Python3</label><label for="__tabbed_1_2">Java</label><label for="__tabbed_1_3">C++</label><label for="__tabbed_1_4">Go</label><label for="__tabbed_1_5">TypeScript</label></div>
+<p>时间复杂度 <span class="arithmatex">\(O(n)\)</span>，其中 <span class="arithmatex">\(n\)</span> 为数组 <span class="arithmatex">\(\textit{arr}\)</span> 的长度。空间复杂度 <span class="arithmatex">\(O(1)\)</span>。</p>
+<div class="tabbed-set tabbed-alternate" data-tabs="1:6"><input checked="checked" id="__tabbed_1_1" name="__tabbed_1" type="radio" /><input id="__tabbed_1_2" name="__tabbed_1" type="radio" /><input id="__tabbed_1_3" name="__tabbed_1" type="radio" /><input id="__tabbed_1_4" name="__tabbed_1" type="radio" /><input id="__tabbed_1_5" name="__tabbed_1" type="radio" /><input id="__tabbed_1_6" name="__tabbed_1" type="radio" /><div class="tabbed-labels"><label for="__tabbed_1_1">Python3</label><label for="__tabbed_1_2">Java</label><label for="__tabbed_1_3">C++</label><label for="__tabbed_1_4">Go</label><label for="__tabbed_1_5">TypeScript</label><label for="__tabbed_1_6">Rust</label></div>
 <div class="tabbed-content">
 <div class="tabbed-block">
 <div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span></span><span class="normal"> 1</span>
@@ -91508,6 +91508,36 @@ <h3 id="_3">方法一：前缀和 + 计数器</h3>
 <span class="p">}</span>
 </code></pre></div></td></tr></table></div>
 </div>
+<div class="tabbed-block">
+<div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span></span><span class="normal"> 1</span>
+<span class="normal"> 2</span>
+<span class="normal"> 3</span>
+<span class="normal"> 4</span>
+<span class="normal"> 5</span>
+<span class="normal"> 6</span>
+<span class="normal"> 7</span>
+<span class="normal"> 8</span>
+<span class="normal"> 9</span>
+<span class="normal">10</span>
+<span class="normal">11</span>
+<span class="normal">12</span>
+<span class="normal">13</span>
+<span class="normal">14</span></pre></div></td><td class="code"><div><pre><span></span><code><span class="k">impl</span><span class="w"> </span><span class="n">Solution</span><span class="w"> </span><span class="p">{</span>
+<span class="w">    </span><span class="k">pub</span><span class="w"> </span><span class="k">fn</span><span class="w"> </span><span class="nf">num_of_subarrays</span><span class="p">(</span><span class="n">arr</span><span class="p">:</span><span class="w"> </span><span class="nb">Vec</span><span class="o">&lt;</span><span class="kt">i32</span><span class="o">&gt;</span><span class="p">)</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="kt">i32</span><span class="w"> </span><span class="p">{</span>
+<span class="w">        </span><span class="k">const</span><span class="w"> </span><span class="n">MOD</span><span class="p">:</span><span class="w"> </span><span class="kt">i32</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mi">1_000_000_007</span><span class="p">;</span>
+<span class="w">        </span><span class="kd">let</span><span class="w"> </span><span class="k">mut</span><span class="w"> </span><span class="n">cnt</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p">[</span><span class="mi">1</span><span class="p">,</span><span class="w"> </span><span class="mi">0</span><span class="p">];</span>
+<span class="w">        </span><span class="kd">let</span><span class="w"> </span><span class="k">mut</span><span class="w"> </span><span class="n">ans</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mi">0</span><span class="p">;</span>
+<span class="w">        </span><span class="kd">let</span><span class="w"> </span><span class="k">mut</span><span class="w"> </span><span class="n">s</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mi">0</span><span class="p">;</span>
+<span class="w">        </span><span class="k">for</span><span class="w"> </span><span class="o">&amp;</span><span class="n">x</span><span class="w"> </span><span class="k">in</span><span class="w"> </span><span class="n">arr</span><span class="p">.</span><span class="n">iter</span><span class="p">()</span><span class="w"> </span><span class="p">{</span>
+<span class="w">            </span><span class="n">s</span><span class="w"> </span><span class="o">+=</span><span class="w"> </span><span class="n">x</span><span class="p">;</span>
+<span class="w">            </span><span class="n">ans</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p">(</span><span class="n">ans</span><span class="w"> </span><span class="o">+</span><span class="w"> </span><span class="n">cnt</span><span class="p">[((</span><span class="n">s</span><span class="w"> </span><span class="o">&amp;</span><span class="w"> </span><span class="mi">1</span><span class="p">)</span><span class="w"> </span><span class="o">^</span><span class="w"> </span><span class="mi">1</span><span class="p">)</span><span class="w"> </span><span class="k">as</span><span class="w"> </span><span class="kt">usize</span><span class="p">])</span><span class="w"> </span><span class="o">%</span><span class="w"> </span><span class="n">MOD</span><span class="p">;</span>
+<span class="w">            </span><span class="n">cnt</span><span class="p">[(</span><span class="n">s</span><span class="w"> </span><span class="o">&amp;</span><span class="w"> </span><span class="mi">1</span><span class="p">)</span><span class="w"> </span><span class="k">as</span><span class="w"> </span><span class="kt">usize</span><span class="p">]</span><span class="w"> </span><span class="o">+=</span><span class="w"> </span><span class="mi">1</span><span class="p">;</span>
+<span class="w">        </span><span class="p">}</span>
+<span class="w">        </span><span class="n">ans</span>
+<span class="w">    </span><span class="p">}</span>
+<span class="p">}</span>
+</code></pre></div></td></tr></table></div>
+</div>
 </div>
 </div>
 <!-- solution:end -->