Algorithm
Problem Name: 470. Implement Rand10() Using Rand7()
Given the API rand7() that generates a uniform random integer in the range [1, 7], write a function rand10() that generates a uniform random integer in the range [1, 10]. You can only call the API rand7(), and you shouldn't call any other API. Please do not use a language's built-in random API.
Each test case will have one internal argument n, the number of times that your implemented function rand10() will be called while testing. Note that this is not an argument passed to rand10().
Example 1:
Input: n = 1 Output: [2]
Example 2:
Input: n = 2 Output: [2,8]
Example 3:
Input: n = 3 Output: [3,8,10]
Constraints:
1 <= n <= 105
Code Examples
#1 Code Example with Java Programming
Code -
Java Programming
class Solution extends SolBase {
public int rand10() {
int temp = 0;
while (true) {
temp = (rand7() - 1) * 7 + (rand7() - 1);
if (temp < 40) {
break;
}
}
return temp % 10 + 1;
}
}
Input
Output
#2 Code Example with Javascript Programming
Code -
Javascript Programming
const rand10 = function() {
let result = 40
while (result >= 40) {
result = 7 * (rand7() - 1) + (rand7() - 1)
}
return (result % 10) + 1
}
Input
Output
#3 Code Example with Python Programming
Code -
Python Programming
class Solution:
def rand10(self):
return sum(rand7() for _ in range(10)) % 10 + 1
Input
Output
#4 Code Example with C# Programming
Code -
C# Programming
using System;
namespace LeetCode
{
/**
* The Rand7() API is already defined in the parent class SolBase.
* public int Rand7();
* @return a random integer in the range 1 to 7
*/
public class _0470_ImplementRand10UsingRand7 : Rand7Base
{
public int Rand10()
{
int r = 40;
while (r >= 40)
r = (Rand7() - 1) * 7 + Rand7() - 1;
return r % 10 + 1;
}
}
public class Rand7Base
{
private readonly Random random = new Random();
public int Rand7()
{
return random.Next(7) + 1;
}
}
}
Input
Output