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/* | ||
* @lc app=leetcode.cn id=470 lang=javascript | ||
* | ||
* [470] 用 Rand7() 实现 Rand10() | ||
* | ||
* https://leetcode-cn.com/problems/implement-rand10-using-rand7/description/ | ||
* | ||
* algorithms | ||
* Medium (55.50%) | ||
* Likes: 218 | ||
* Dislikes: 0 | ||
* Total Accepted: 31.8K | ||
* Total Submissions: 57.2K | ||
* Testcase Example: '1' | ||
* | ||
* 已有方法 rand7 可生成 1 到 7 范围内的均匀随机整数,试写一个方法 rand10 生成 1 到 10 范围内的均匀随机整数。 | ||
* | ||
* 不要使用系统的 Math.random() 方法。 | ||
* | ||
* | ||
* | ||
* | ||
* | ||
* | ||
* 示例 1: | ||
* | ||
* | ||
* 输入: 1 | ||
* 输出: [7] | ||
* | ||
* | ||
* 示例 2: | ||
* | ||
* | ||
* 输入: 2 | ||
* 输出: [8,4] | ||
* | ||
* | ||
* 示例 3: | ||
* | ||
* | ||
* 输入: 3 | ||
* 输出: [8,1,10] | ||
* | ||
* | ||
* | ||
* | ||
* 提示: | ||
* | ||
* | ||
* rand7 已定义。 | ||
* 传入参数: n 表示 rand10 的调用次数。 | ||
* | ||
* | ||
* | ||
* | ||
* 进阶: | ||
* | ||
* | ||
* rand7()调用次数的 期望值 是多少 ? | ||
* 你能否尽量少调用 rand7() ? | ||
* | ||
* | ||
*/ | ||
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// @lc code=start | ||
/** | ||
* The rand7() API is already defined for you. | ||
* var rand7 = function() {} | ||
* @return {number} a random integer in the range 1 to 7 | ||
*/ | ||
var rand10 = function() { | ||
//https://leetcode-cn.com/problems/implement-rand10-using-rand7/solution/xiang-xi-si-lu-ji-you-hua-si-lu-fen-xi-zhu-xing-ji/ | ||
// 首先得到一个数 | ||
let num = (rand7() - 1) * 7 + rand7(); | ||
// 只要它还大于40,那你就给我不断生成吧 | ||
while (num > 40) { | ||
num = (rand7() - 1) * 7 + rand7(); | ||
} | ||
// 返回结果,+1是为了解决 40%10为0的情况 | ||
return 1 + num % 10; | ||
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}; | ||
// @lc code=end | ||
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