找出数字 d 在[0..n]
给定一个数字 n 和一个数字 d，计算从 0 到 n 范围内 d 的所有出现次数。 示例:
Input : n = 25
d = 2
Output : 9
The occurrences are 2, 12, 20, 21
22 (Two occurrences), 23, 24, 25
Input : n = 25
d = 3
Output :3
The occurrences are 3, 13, 23
Input : n = 32
d = 3
Output : 6
The occurrences are 3, 13, 23, 30, 31, 32
d 的第一次出现不能在数字 d 之前，所以我们从 d 开始迭代，反复做以下检查。除了步骤 2.a 和 2.b 中提到的情况外，我们大多数情况下都会将数字加 10(在步骤 2 中) 步骤 1 :检查数字的最后一位是否等于 d，如果是，则递增计数。 第二步 : a)如果数完全能被 10 整除，那么计数和数都要递增(例如，如果我们达到数 30，而数 30 完全能被 10 整除，并且 d=3，那么我们必须从 31-39 中对所有数进行计数，这就是我们为什么要递增 1 并递增 1 的原因) b)否则，如果数的第一个数字比 d 小 1，那么这意味着我们已经到了必须将数递增 10 并从中减去 d 的那一行。例如，如果 d=3，我们达到 23，那么我们将该数增加 23+10-3 = 30) c)否则只增加 10。(例如:d=3，itr=3，然后递增 10，即 13，23) 步骤 3:- 返回计数。
C++
// C++ program to count appearances of
// a digit 'd' in range from [0..n]
#include <bits/stdc++.h>
using namespace std;
int getOccurence(int n, int d)
{
int result = 0; // Initialize result
// Count appearances in numbers starting
// from d.
int itr = d;
while (itr <= n)
{
// When the last digit is equal to d
if (itr%10 == d)
result++;
// When the first digit is equal to d then
if (itr != 0 && itr/10 == d)
{
// increment result as well as number
result++;
itr++;
}
// In case of reverse of number such as 12 and 21
else if (itr/10 == d-1)
itr = itr + (10 - d);
else
itr = itr+10;
}
return result;
}
// Driver code
int main(void)
{
int n = 11, d = 1;
cout << getOccurence(n, d);
return 0;
}
Java 语言(一种计算机语言，尤用于创建网站)
// java program to count appearances of
// a digit 'd' in range from [0..n]
import java.*;
public class GFG {
static int getOccurence(int n, int d)
{
// Initialize result
int result = 0;
// Count appearances in numbers
// starting from d.
int itr = d;
while (itr <= n)
{
// When the last digit is
// equal to d
if (itr % 10 == d)
result++;
// When the first digit is
// equal to d then
if (itr != 0 && itr/10 == d)
{
// increment result as
// well as number
result++;
itr++;
}
// In case of reverse of number
// such as 12 and 21
else if (itr/10 == d-1)
itr = itr + (10 - d);
else
itr = itr + 10;
}
return result;
}
// Driver code
public static void main (String[] args)
{
int n = 11, d = 1;
System.out.println(getOccurence(n, d) );
}
}
// This code is contributed by Sam007.
Python 3
# Python3 program to count appearances
# of a digit 'd' in range from [0..n]
import math;
def getOccurence(n, d):
# Initialize result
result = 0;
# Count appearances in numbers
# starting from d.
itr = d;
while(itr <= n):
# When the last digit is equal to d
if (itr % 10 == d):
result += 1;
# When the first digit is equal to d then
if (itr != 0 and math.floor(itr / 10) == d):
# increment result as well as number
result += 1;
itr += 1;
# In case of reverse of number
# such as 12 and 21
elif (math.floor(itr / 10) == d - 1):
itr = itr + (10 - d);
else:
itr = itr + 10;
return result;
# Driver code
n = 11;
d = 1;
print(getOccurence(n, d));
# This code is contributed by mits
C
// C# program to count appearances of
// a digit 'd' in range from [0..n]
using System;
public class GFG {
static int getOccurence(int n, int d)
{
// Initialize result
int result = 0;
// Count appearances in numbers
// starting from d.
int itr = d;
while (itr <= n)
{
// When the last digit is
// equal to d
if (itr % 10 == d)
result++;
// When the first digit is
// equal to d then
if (itr != 0 && itr/10 == d)
{
// increment result as
// well as number
result++;
itr++;
}
// In case of reverse of number
// such as 12 and 21
else if (itr/10 == d-1)
itr = itr + (10 - d);
else
itr = itr + 10;
}
return result;
}
// Driver code
public static void Main()
{
int n = 11, d = 1;
Console.Write(getOccurence(n, d));
}
}
// This code is contributed by Sam007.
服务器端编程语言（Professional Hypertext Preprocessor 的缩写）
<?php
// PHP program to count appearances of
// a digit 'd' in range from [0..n]
function getOccurence($n, $d)
{
// Initialize result
$result = 0;
// Count appearances in numbers
// starting from d.
$itr = $d;
while($itr <= $n)
{
// When the last digit
// is equal to d
if ($itr % 10 == $d)
$result++;
// When the first digit
// is equal to d then
if ($itr != 0 && floor($itr / 10) == $d)
{
// increment result as
// well as number
$result++;
$itr++;
}
// In case of reverse of
// number such as 12 and 21
else if (floor($itr / 10) == $d - 1)
$itr = $itr + (10 - $d);
else
$itr = $itr + 10;
}
return $result;
}
// Driver code
$n = 11;
$d = 1;
echo getOccurence($n, $d);
// This code is contributed by nitin mittal.
?>
java 描述语言
<script>
// Javascript program to count appearances of
// a digit 'd' in range from [0..n]
function getOccurence(n, d)
{
// Initialize result
let result = 0;
// Count appearances in numbers
// starting from d.
let itr = d;
while(itr <= n)
{
// When the last digit
// is equal to d
if (itr % 10 == d)
result++;
// When the first digit
// is equal to d then
if (itr != 0 && Math.floor(itr / 10) == d)
{
// increment result as
// well as number
result++;
itr++;
}
// In case of reverse of
// number such as 12 and 21
else if (Math.floor(itr / 10) == d - 1)
itr = itr + (10 - d);
else
itr = itr + 10;
}
return result;
}
// Driver code
let n = 11;
let d = 1;
document.write(getOccurence(n, d));
// This code is contributed by _saurabh_jaiswal.
</script>
输出:
4
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