不包含 9 的 n 位数的个数
原文:https://www . geesforgeks . org/numbers-n-digital-numbers-not-contain-9/
给定一个数字 n，找出可以形成多少个不包含 9 的 n 位数。 示例:
Input : 1
Output : 8
Explanation :
Except 9, all numbers are possible
Input : 2
Output : 72
Explanation :
Except numbers from 90 - 99 and all
two digit numbers that does not end
with 9 are possible.
可以形成的 n 位数字的总数将是 910^(n-1)，因为除了第一个位置之外，所有数字都可以用 10 个数字(0-9)填充。如果从列表中删除数字 9，那么 n 个数字的总数将是 89^(n-1). 以下是上述思路的实现:
C++
// CPP program to find number of n
// digit numbers that do not
// contain 9 as it's digit
#include <bits/stdc++.h>
using namespace std;
// function to find number of
// n digit numbers possible
int totalNumber(int n)
{
return 8*pow(9, n - 1);
}
// driver function
int main()
{
int n = 3;
cout << totalNumber(n);
return 0;
}
Java 语言(一种计算机语言，尤用于创建网站)
// Java program to find number of
// n digit numbers that do not
// contain 9 as it's digit
import java.io.*;
public class GFG
{
// function to find number of
// n digit numbers possible
static int totalNumber(int n)
{
return 8 * (int)Math.pow(9, n - 1);
}
// Driver Code
static public void main (String[] args)
{
int n = 3;
System.out.println(totalNumber(n));
}
}
// This code is contributed by vt_m.
Python 3
# python program to find number of n
# digit numbers that do not
# contain 9 as it's digit
# function to find number of
# n digit numbers possible
def totalNumber(n):
return 8 * pow(9, n - 1);
# driver function
n = 3
print(totalNumber(n))
# This code is contributed by Sam007
C
// C# program to find number of
// n digit numbers that do not
// contain 9 as it's digit
using System;
public class GFG
{
// function to find number of
// n digit numbers possible
static int totalNumber(int n)
{
return 8 * (int)Math.Pow(9, n - 1);
}
// Driver Code
static public void Main ()
{
int n = 3;
Console.WriteLine(totalNumber(n));
}
}
// This code is contributed by vt_m.
服务器端编程语言（Professional Hypertext Preprocessor 的缩写）
<?php
// php program to find number of n
// digit numbers that do not
// contain 9 as it's digit
// function to find number of
// n digit numbers possible
function totalNumber($n)
{
return 8 * pow(9, $n - 1);
}
// driver function
$n = 3;
print(totalNumber($n))
// This code is contributed by Sam007
?>
java 描述语言
<script>
// Javascript program to find number of
// n digit numbers that do not
// contain 9 as it's digit
// function to find number of
// n digit numbers possible
function totalNumber(n)
{
return 8 * Math.pow(9, n - 1);
}
// Driver code
let n = 3;
document.write(totalNumber(n));
// This code is contributed by code_hunt.
</script>
输出:
648
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