Subtract the count of all-odd subarrays from the total to get the answer.
Code

[{"language":"C++","code":"class Solution {\npublic:\n    long long evenProduct(vector<int>& nums) {\n        long long n = nums.size(), ans = n * (n + 1) / 2, odd = 0, cnt = 0;\n        for (int x : nums) {\n            if (x % 2 == 1) {\n                ++cnt;\n            } else {\n                odd += cnt * (cnt + 1) / 2;\n                cnt = 0;\n            }\n        }\n        odd += cnt * (cnt + 1) / 2;\n        return ans - odd;\n    }\n};","lang":"cpp","html":"<pre class=\"shiki shiki-themes github-light github-dark\" style=\"background-color:#fff;--shiki-dark-bg:#24292e;color:#24292e;--shiki-dark:#e1e4e8\" tabindex=\"0\"><code><span class=\"line\"><span style=\"color:#D73A49;--shiki-dark:#F97583\">class</span><span style=\"color:#6F42C1;--shiki-dark:#B392F0\"> Solution</span><span style=\"color:#24292E;--shiki-dark:#E1E4E8\"> {</span></span>\n<span class=\"line\"><span style=\"color:#D73A49;--shiki-dark:#F97583\">public:</span></span>\n<span class=\"line\"><span style=\"color:#D73A49;--shiki-dark:#F97583\">    long</span><span style=\"color:#D73A49;--shiki-dark:#F97583\"> long</span><span style=\"color:#6F42C1;--shiki-dark:#B392F0\"> evenProduct</span><span style=\"color:#24292E;--shiki-dark:#E1E4E8\">(</span><span style=\"color:#6F42C1;--shiki-dark:#B392F0\">vector</span><span style=\"color:#24292E;--shiki-dark:#E1E4E8\">&#x3C;</span><span style=\"color:#D73A49;--shiki-dark:#F97583\">int</span><span style=\"color:#24292E;--shiki-dark:#E1E4E8\">></span><span style=\"color:#D73A49;--shiki-dark:#F97583\">&#x26;</span><span style=\"color:#E36209;--shiki-dark:#FFAB70\"> nums</span><span style=\"color:#24292E;--shiki-dark:#E1E4E8\">) {</span></span>\n<span class=\"line\"><span style=\"color:#D73A49;--shiki-dark:#F97583\">        long</span><span style=\"color:#D73A49;--shiki-dark:#F97583\"> long</span><span style=\"color:#24292E;--shiki-dark:#E1E4E8\"> n </span><span style=\"color:#D73A49;--shiki-dark:#F97583\">=</span><span style=\"color:#24292E;--shiki-dark:#E1E4E8\"> nums.</span><span style=\"color:#6F42C1;--shiki-dark:#B392F0\">size</span><span style=\"color:#24292E;--shiki-dark:#E1E4E8\">(), ans </span><span style=\"color:#D73A49;--shiki-dark:#F97583\">=</span><span style=\"color:#24292E;--shiki-dark:#E1E4E8\"> n </span><span style=\"color:#D73A49;--shiki-dark:#F97583\">*</span><span style=\"color:#24292E;--shiki-dark:#E1E4E8\"> (n </span><span style=\"color:#D73A49;--shiki-dark:#F97583\">+</span><span style=\"color:#005CC5;--shiki-dark:#79B8FF\"> 1</span><span style=\"color:#24292E;--shiki-dark:#E1E4E8\">) </span><span style=\"color:#D73A49;--shiki-dark:#F97583\">/</span><span style=\"color:#005CC5;--shiki-dark:#79B8FF\"> 2</span><span style=\"color:#24292E;--shiki-dark:#E1E4E8\">, odd </span><span style=\"color:#D73A49;--shiki-dark:#F97583\">=</span><span style=\"color:#005CC5;--shiki-dark:#79B8FF\"> 0</span><span style=\"color:#24292E;--shiki-dark:#E1E4E8\">, cnt </span><span style=\"color:#D73A49;--shiki-dark:#F97583\">=</span><span style=\"color:#005CC5;--shiki-dark:#79B8FF\"> 0</span><span style=\"color:#24292E;--shiki-dark:#E1E4E8\">;</span></span>\n<span class=\"line\"><span style=\"color:#D73A49;--shiki-dark:#F97583\">        for</span><span style=\"color:#24292E;--shiki-dark:#E1E4E8\"> (</span><span style=\"color:#D73A49;--shiki-dark:#F97583\">int</span><span style=\"color:#24292E;--shiki-dark:#E1E4E8\"> x : nums) {</span></span>\n<span class=\"line\"><span
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