用数字根 D 打印一个包含 K 位数字的数字
原文:https://www . geesforgeks . org/print-a-number-contain-k-digits-digital-root-d/
给定一个数字根“D”和数字个数“K”。任务是打印一个包含 K 位数字的数字，该数字的数字根等于 d。如果该数字不存在，则打印“-1”。
示例:
Input: D = 4, K = 4
Output: 4000
No. of digits is 4.
Sum of digits is also 4.
Input: D = 0, K = 1
Output: 0
方法:解决这个问题的一个关键观察是，在一个数字上附加任何数量的 0 都不会改变其数字根。因此 D 后跟(K-1) 0 的是一个简单的解决方案。
D 为 0，K 不为 1 的特殊情况没有解决办法，因为数字根为 0 的唯一数字本身就是 0。
下面是上述方法的实现:
C++
// C++ implementation of the above approach
#include <bits/stdc++.h>
using namespace std;
// Function to find a number
void printNumberWithDR(int k, int d)
{
// If d is 0 k has to be 1
if (d == 0 && k != 1)
cout << "-1";
else {
cout << d;
k--;
// Print k-1 zeroes
while (k--)
cout << "0";
}
}
// Driver code
int main()
{
int k = 4, d = 4;
printNumberWithDR(k, d);
return 0;
}
Java 语言(一种计算机语言，尤用于创建网站)
// Java implementation of the above approach
import java.io.*;
class GFG {
// Function to find a number
static void printNumberWithDR(int k, int d)
{
// If d is 0 k has to be 1
if (d == 0 && k != 1)
System.out.print( "-1");
else {
System.out.print(d);
k--;
// Print k-1 zeroes
while (k-->0)
System.out.print( "0");
}
}
// Driver code
public static void main (String[] args) {
int k = 4, d = 4;
printNumberWithDR(k, d);
}
}
//This code is contributed by inder_verma..
Python 3
# Python3 implementation of
# the above approach
# Function to find a number
def printNumberWithDR( k, d ) :
# If d is 0, k has to be 1
if d == 0 and k != 1 :
print(-1, end = "")
else :
print(d, end = "")
k -= 1
# Print k-1 zeroes
while k :
print(0,end = "")
k -= 1
# Driver code
if __name__ == "__main__" :
k, d = 4, 4
# Function call
printNumberWithDR( k, d )
# This code is contributed by
# ANKITRAI1
C
// C# implementation of the above approach
using System;
class GFG {
// Function to find a number
static void printNumberWithDR(int k, int d)
{
// If d is 0 k has to be 1
if (d == 0 && k != 1)
Console.Write( "-1");
else {
Console.Write(d);
k--;
// Print k-1 zeroes
while (k-->0)
Console.Write( "0");
}
}
// Driver code
static public void Main ()
{
int k = 4, d = 4;
printNumberWithDR(k, d);
}
}
// This code is contributed by ajit.
服务器端编程语言（Professional Hypertext Preprocessor 的缩写）
<?php
// PHP implementation of the above approach
// Function to find a number
function printNumberWithDR($k, $d)
{
// If d is 0 k has to be 1
if ($d == 0 && $k != 1)
echo "-1";
else
{
echo $d;
$k--;
// Print k-1 zeroes
while ($k--)
echo "0";
}
}
// Driver code
$k = 4;
$d = 4;
printNumberWithDR($k, $d);
// This code is contributed
// by akt_mit
?>
java 描述语言
<script>
// Javascript implementation of the above approach
// Function to find a number
function printNumberWithDR(k, d)
{
// If d is 0 k has to be 1
if (d == 0 && k != 1)
document.write("-1");
else
{
document.write(d);
k--;
// Print k-1 zeroes
while (k-->0)
document.write("0");
}
}
// Driver Code
var k = 4, d = 4;
printNumberWithDR(k, d);
// This code is contributed by Ankita saini
</script>
Output:
4000
时间复杂度: O(K)
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