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If both a and n-a are prime, return [a, n-a].
Code

[{"language":"C++","code":"class Solution {\npublic:\n\tvector<int> primePairSum(int n) {\n\t\tvector<bool> isPrime(n+1, true);\n\t\tisPrime[0] = isPrime[1] = false;\n\t\tfor (int i = 2; i * i <= n; ++i) {\n\t\t\tif (isPrime[i]) {\n\t\t\t\tfor (int j = i * i; j <= n; j += i) isPrime[j] = false;\n\t\t\t}\n\t\t}\n\t\tfor (int a = 2; a <= n/2; ++a) {\n\t\t\tif (isPrime[a] && isPrime[n-a]) return {a, n-a};\n\t\t}\n\t\treturn {};\n\t}\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:#6F42C1;--shiki-dark:#B392F0\">\tvector</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:#6F42C1;--shiki-dark:#B392F0\">primePairSum</span><span style=\"color:#24292E;--shiki-dark:#E1E4E8\">(</span><span style=\"color:#D73A49;--shiki-dark:#F97583\">int</span><span style=\"color:#E36209;--shiki-dark:#FFAB70\"> n</span><span style=\"color:#24292E;--shiki-dark:#E1E4E8\">) {</span></span>\n<span class=\"line\"><span style=\"color:#24292E;--shiki-dark:#E1E4E8\">\t\tvector</span><span style=\"color:#D73A49;--shiki-dark:#F97583\">&#x3C;bool></span><span style=\"color:#6F42C1;--shiki-dark:#B392F0\"> isPrime</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:#005CC5;--shiki-dark:#79B8FF\">true</span><span style=\"color:#24292E;--shiki-dark:#E1E4E8\">);</span></span>\n<span class=\"line\"><span style=\"color:#24292E;--shiki-dark:#E1E4E8\">\t\tisPrime[</span><span style=\"color:#005CC5;--shiki-dark:#79B8FF\">0</span><span style=\"color:#24292E;--shiki-dark:#E1E4E8\">] </span><span style=\"color:#D73A49;--shiki-dark:#F97583\">=</span><span style=\"color:#24292E;--shiki-dark:#E1E4E8\"> isPrime[</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\"> false</span><span style=\"color:#24292E;--shiki-dark:#E1E4E8\">;&#
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