在给定范围内选择一个随机数得到一个完美平方的概率
给定表示一个范围的两个整数 L 和 R ，任务是当在范围 L 到 R 中选择一个随机数时，找到得到一个完美平方数的概率。 举例:
输入: L = 6，R = 20 输出: 0.133333 解释: 范围内的完美方块【6，20】= { 9，16} = > 2 完美方块 范围内的总数【6，20】= 15 概率= 2 / 15 = 0.133333 输入: L = 16
方法:这个问题的关键观察是从 0 到一个数范围内的完美平方的计数可以用给定的公式计算:
//0 到 N 范围内的完美正方形的计数为 完美正方形的计数=地板(sqrt(N))
类似地，在给定范围内的完美正方形的计数可以借助于上述公式计算如下:
完美正方形的计数[L，R] =地板(sqrt(R))–天花板(sqrt(L)) + 1 范围内的总数= R–L+1
以下是上述方法的实现:
C++
// C++ implementation to find the
// probability of getting a
// perfect square number
#include <bits/stdc++.h>
using namespace std;
// Function to return the probability
// of getting a perfect square
// number in a range
float findProb(int l, int r)
{
// Count of perfect squares
float countOfPS = floor(sqrt(r)) - ceil(sqrt(l)) + 1;
// Total numbers in range l to r
float total = r - l + 1;
// Calculating probability
float prob = (float)countOfPS / (float)total;
return prob;
}
// Driver Code
int main()
{
int L = 16, R = 25;
cout << findProb(L, R);
return 0;
}
Java 语言(一种计算机语言，尤用于创建网站)
// Java implementation to find the
// probability of getting a
// perfect square number
class GFG{
// Function to return the probability
// of getting a perfect square
// number in a range
static float findProb(int l, int r)
{
// Count of perfect squares
float countOfPS = (float) (Math.floor(Math.sqrt(r)) -
Math.ceil(Math.sqrt(l)) + 1);
// Total numbers in range l to r
float total = r - l + 1;
// Calculating probability
float prob = (float)countOfPS / (float)total;
return prob;
}
// Driver Code
public static void main(String[] args)
{
int L = 16, R = 25;
System.out.print(findProb(L, R));
}
}
// This code is contributed by Amit Katiyar
Python 3
# Python3 implementation to find
# the probability of getting a
# perfect square number
import math
# Function to return the probability
# of getting a perfect square
# number in a range
def findProb(l, r):
# Count of perfect squares
countOfPS = (math.floor(math.sqrt(r)) -
math.ceil(math.sqrt(l)) + 1)
# Total numbers in range l to r
total = r - l + 1
# Calculating probability
prob = countOfPS / total
return prob
# Driver code
if __name__=='__main__':
L = 16
R = 25
print(findProb(L, R))
# This code is contributed by rutvik_56
C
// C# implementation to find the probability
// of getting a perfect square number
using System;
class GFG{
// Function to return the probability
// of getting a perfect square
// number in a range
static float findProb(int l, int r)
{
// Count of perfect squares
float countOfPS = (float)(Math.Floor(Math.Sqrt(r)) -
Math.Ceiling(Math.Sqrt(l)) + 1);
// Total numbers in range l to r
float total = r - l + 1;
// Calculating probability
float prob = (float)countOfPS / (float)total;
return prob;
}
// Driver Code
public static void Main(String[] args)
{
int L = 16, R = 25;
Console.Write(findProb(L, R));
}
}
// This code is contributed by Amit Katiyar
java 描述语言
<script>
// Javascript implementation to find the
// probability of getting a
// perfect square number
// Function to return the probability
// of getting a perfect square
// number in a range
function findProb(l, r)
{
// Count of perfect squares
var countOfPS = (Math.floor(Math.sqrt(r)) -
Math.ceil(Math.sqrt(l)) + 1);
// Total numbers in range l to r
var total = r - l + 1;
// Calculating probability
var prob = countOfPS / total;
return prob;
}
// Driver code
var L = 16, R = 25;
// Function Call
document.write(findProb(L, R));
// This code is contributed by Khushboogoyal499
</script>
Output:
0.2
时间复杂度: O(1)
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