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            "title": "Implement Rand10() Using Rand7()",
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            "content": "<p>Given the <strong>API</strong> <code>rand7()</code> that generates a uniform random integer in the range <code>[1, 7]</code>, write a function <code>rand10()</code> that generates a uniform random integer in the range <code>[1, 10]</code>. You can only call the API <code>rand7()</code>, and you shouldn&#39;t call any other API. Please <strong>do not</strong> use a language&#39;s built-in random API.</p>\n\n<p>Each test case will have one <strong>internal</strong> argument <code>n</code>, the number of times that your implemented function <code>rand10()</code> will be called while testing. Note that this is <strong>not an argument</strong> passed to <code>rand10()</code>.</p>\n\n<p>&nbsp;</p>\n<p><strong>Example 1:</strong></p>\n<pre><strong>Input:</strong> n = 1\n<strong>Output:</strong> [2]\n</pre><p><strong>Example 2:</strong></p>\n<pre><strong>Input:</strong> n = 2\n<strong>Output:</strong> [2,8]\n</pre><p><strong>Example 3:</strong></p>\n<pre><strong>Input:</strong> n = 3\n<strong>Output:</strong> [3,8,10]\n</pre>\n<p>&nbsp;</p>\n<p><strong>Constraints:</strong></p>\n\n<ul>\n\t<li><code>1 &lt;= n &lt;= 10<sup>5</sup></code></li>\n</ul>\n\n<p>&nbsp;</p>\n<p><strong>Follow up:</strong></p>\n\n<ul>\n\t<li>What is the <a href=\"https://en.wikipedia.org/wiki/Expected_value\" target=\"_blank\">expected value</a> for the number of calls to <code>rand7()</code> function?</li>\n\t<li>Could you minimize the number of calls to <code>rand7()</code>?</li>\n</ul>\n",
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                    "code": "// The rand7() API is already defined for you.\n// int rand7();\n// @return a random integer in the range 1 to 7\n\nclass Solution {\npublic:\n    int rand10() {\n        \n    }\n};",
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                    "code": "/**\n * The rand7() API is already defined in the parent class SolBase.\n * public int rand7();\n * @return a random integer in the range 1 to 7\n */\nclass Solution extends SolBase {\n    public int rand10() {\n        \n    }\n}",
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                    "code": "# The rand7() API is already defined for you.\n# def rand7():\n# @return a random integer in the range 1 to 7\n\nclass Solution(object):\n    def rand10(self):\n        \"\"\"\n        :rtype: int\n        \"\"\"\n        ",
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                    "code": "/**\n * The Rand7() API is already defined in the parent class SolBase.\n * public int Rand7();\n * @return a random integer in the range 1 to 7\n */\npublic class Solution : SolBase {\n    public int Rand10() {\n        \n    }\n}",
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                    "code": "/**\n * The rand7() API is already defined in the parent class SolBase.\n * func rand7() -> Int = {}\n * @return a random integer in the range 1 to 7\n */\nclass Solution : SolBase {\n    func rand10() -> Int {\n        \n    }\n}",
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