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feat: add solutions to lc problem: No.0470 (doocs#1353)
No.0470.Implement Rand10() Using Rand7()
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‎solution/0400-0499/0470.Implement Rand10() Using Rand7()/README.md

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<!-- 这里可写通用的实现逻辑 -->
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**方法一：拒绝采样**
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我们可以使用拒绝采样的方法实现等概率生成任意区间的随机数。拒绝采样的思路是如果生成的随机数落在我们希望的区间内，那么就返回该随机数，否则会不断生成直到生成一个落在区间内的随机数为止。
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对于本题，我们可以通过调用 $rand7()$ 两次来实现生成 $[1,10]$ 以内的随机数，具体如下：
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我们生成一个大于等于 $1$ 且小于等于 $40$ 的整数 $x$，其中等概率生成的方式为 $x = (rand7() - 1) \times 7 + rand7()$，然后，我们返回 $x \bmod 10 + 1$ 即可。
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期望时间复杂度为 $O(1)$，但是最坏情况下会达到无穷大的时间复杂度。空间复杂度为 $O(1)$。
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<!-- tabs:start -->
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### **Python3**
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<!-- 这里可写当前语言的特殊实现逻辑 -->
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```python
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# The rand7() API is already defined for you.
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# def rand7():
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# @return a random integer in the range 1 to 7
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class Solution:
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def rand10(self):
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"""
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:rtype: int
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"""
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while 1:
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i = rand7() - 1
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j = rand7()
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x = i * 7 + j
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if x <= 40:
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return x % 10 + 1
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```
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### **Java**
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<!-- 这里可写当前语言的特殊实现逻辑 -->
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```java
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/**
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* The rand7() API is already defined in the parent class SolBase.
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* public int rand7();
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* @return a random integer in the range 1 to 7
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*/
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class Solution extends SolBase {
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public int rand10() {
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while (true) {
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int i = rand7() - 1;
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int j = rand7();
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int x = i * 7 + j;
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if (x <= 40) {
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return x % 10 + 1;
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}
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}
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}
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}
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```
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### **C++**
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```cpp
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// The rand7() API is already defined for you.
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// int rand7();
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// @return a random integer in the range 1 to 7
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class Solution {
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public:
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int rand10() {
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while (1) {
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int i = rand7() - 1;
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int j = rand7();
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int x = i * 7 + j;
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if (x <= 40) {
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return x % 10 + 1;
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}
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}
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}
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};
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```
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### **Go**
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```go
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func rand10() int {
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for {
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i := rand7() - 1
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j := rand7()
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x := i*7 + j
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if x <= 40 {
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return x%10 + 1
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}
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}
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}
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```
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### **TypeScript**
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```ts
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/**
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* The rand7() API is already defined for you.
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* function rand7(): number {}
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* @return a random integer in the range 1 to 7
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*/
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function rand10(): number {
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while (true) {
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const i = rand7() - 1;
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const j = rand7();
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const x = i * 7 + j;
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if (x <= 40) {
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return (x % 10) + 1;
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}
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}
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}
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```
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### **...**

‎solution/0400-0499/0470.Implement Rand10() Using Rand7()/README_EN.md

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### **Python3**
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```python
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# The rand7() API is already defined for you.
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# def rand7():
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# @return a random integer in the range 1 to 7
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class Solution:
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def rand10(self):
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"""
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:rtype: int
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"""
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while 1:
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i = rand7() - 1
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j = rand7()
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x = i * 7 + j
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if x <= 40:
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return x % 10 + 1
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```
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### **Java**
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```java
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/**
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* The rand7() API is already defined in the parent class SolBase.
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* public int rand7();
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* @return a random integer in the range 1 to 7
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*/
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class Solution extends SolBase {
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public int rand10() {
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while (true) {
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int i = rand7() - 1;
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int j = rand7();
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int x = i * 7 + j;
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if (x <= 40) {
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return x % 10 + 1;
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}
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}
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}
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}
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```
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### **C++**
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```cpp
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// The rand7() API is already defined for you.
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// int rand7();
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// @return a random integer in the range 1 to 7
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class Solution {
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public:
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int rand10() {
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while (1) {
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int i = rand7() - 1;
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int j = rand7();
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int x = i * 7 + j;
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if (x <= 40) {
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return x % 10 + 1;
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}
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}
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}
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};
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```
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### **Go**
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```go
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func rand10() int {
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for {
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i := rand7() - 1
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j := rand7()
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x := i*7 + j
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if x <= 40 {
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return x%10 + 1
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}
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}
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}
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```
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### **TypeScript**
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```ts
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/**
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* The rand7() API is already defined for you.
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* function rand7(): number {}
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* @return a random integer in the range 1 to 7
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*/
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function rand10(): number {
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while (true) {
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const i = rand7() - 1;
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const j = rand7();
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const x = i * 7 + j;
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if (x <= 40) {
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return (x % 10) + 1;
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}
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}
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}
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```
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### **...**

‎solution/0400-0499/0470.Implement Rand10() Using Rand7()/Solution.cpp

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// The rand7() API is already defined for you.
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// int rand7();
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// @return a random integer in the range 1 to 7
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class Solution {
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public:
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int rand10() {
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while (1) {
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int i = rand7() - 1;
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int j = rand7();
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int x = i * 7 + j;
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if (x <= 40) {
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return x % 10 + 1;
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}
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}
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}
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};

‎solution/0400-0499/0470.Implement Rand10() Using Rand7()/Solution.go

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func rand10() int {
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for {
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i := rand7() - 1
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j := rand7()
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x := i*7 + j
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if x <= 40 {
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return x%10 + 1
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}
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}
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}

‎solution/0400-0499/0470.Implement Rand10() Using Rand7()/Solution.java

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/**
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* The rand7() API is already defined in the parent class SolBase.
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* public int rand7();
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* @return a random integer in the range 1 to 7
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*/
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class Solution extends SolBase {
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public int rand10() {
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while (true) {
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int i = rand7() - 1;
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int j = rand7();
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int x = i * 7 + j;
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if (x <= 40) {
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return x % 10 + 1;
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}
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}
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}
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}

‎solution/0400-0499/0470.Implement Rand10() Using Rand7()/Solution.py

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# The rand7() API is already defined for you.
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# def rand7():
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# @return a random integer in the range 1 to 7
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class Solution:
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def rand10(self):
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"""
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:rtype: int
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"""
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while 1:
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i = rand7() - 1
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j = rand7()
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x = i * 7 + j
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if x <= 40:
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return x % 10 + 1

‎solution/0400-0499/0470.Implement Rand10() Using Rand7()/Solution.ts

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/**
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* The rand7() API is already defined for you.
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* function rand7(): number {}
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* @return a random integer in the range 1 to 7
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*/
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function rand10(): number {
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while (true) {
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const i = rand7() - 1;
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const j = rand7();
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const x = i * 7 + j;
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if (x <= 40) {
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return (x % 10) + 1;
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}
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}
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}

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