给定整数N ，任务是查找具有最大大小的组数。从1到N的每个数字都根据其数字的乘积进行分组。
例子：
Input: N = 13
Output: 3
Explanation:
There are 9 groups in total, they are grouped according to the product of its digits
of numbers from 1 to 13: [1, 11] [2, 12] [3, 13] [4] [5] [6] [7] [8] [9].
Out of these, 3 groups have the largest size that is 2.
Input: N = 2
Output: 2
Explanation:
There are 2 groups in total, they are grouped according to the product of its digits
of numbers from 1 to 2: [1] [2].
Out of these, 2 groups have the largest size that is 1.
方法：
为了解决上述问题，我们必须使用哈希图存储每个元素的数字从1到N的乘积，并在重复时增加其频率。然后，我们必须在哈希图中找到最大频率，该最大频率将是该组的最大大小。最后，对与最大组具有相同频率计数的所有组进行计数，然后返回计数。
下面是上述方法的实现：
C++
// C++ implementation to Count the
// groups having largest size while
// grouping is according to
// the product of its digits
#include
using namespace std;
// Function to find out product of digit
int digit_prod(int x)
{
int prod = 1;
// calculate product
while (x) {
prod *= x % 10;
x = x / 10;
}
// return the product of digits
return prod;
}
// Function to find the count
int find_count(int n)
{
// hash map for
// counting frequency
map mpp;
for (int i = 1; i <= n; i++) {
// counting freq of each element
mpp[digit_prod(i)] += 1;
}
int ans = 1;
int maxm = 0;
for (auto x : mpp) {
// find the maximum
if (x.second > maxm) {
maxm = x.second;
ans = 1;
}
else if (x.second == maxm) {
// count the number of groups having
// size of equal to largest group.
ans++;
}
}
return ans;
}
// Driver code
int main()
{
// initialise N
int N = 13;
cout << find_count(N);
return 0;
} Java
// Java implementation to Count the
// groups having largest size while
// grouping is according to
// the product of its digits
import java.io.*;
import java.util.*;
class GFG{
// Function to find out product of digit
static int digit_prod(int x)
{
int prod = 1;
// Calculate product
while (x != 0)
{
prod *= x % 10;
x = x / 10;
}
// Return the product of digits
return prod;
}
// Function to find the count
static int find_count(int n)
{
// Hash map for counting frequency
Map mpp = new HashMap<>();
for(int i = 1; i <= n; i++)
{
// Counting freq of each element
int t = digit_prod(i);
mpp.put(t, mpp.getOrDefault(t, 0) + 1);
}
int ans = 1;
int maxm = 0;
for(Integer x : mpp.values())
{
// Find the maximum
if (x > maxm)
{
maxm = x;
ans = 1;
}
else if (x == maxm)
{
// Count the number of groups having
// size of equal to largest group.
ans++;
}
}
return ans;
}
// Driver Code
public static void main(String args[])
{
// Initialise N
int N = 13;
System.out.print(find_count(N));
}
}
// This code is contributed by offbeat Python3
# Python3 implementation to Count the
# groups having largest size while
# grouping is according to
# the product of its digits
# Function to find out product of digit
def digit_prod(x) :
prod = 1
# calculate product
while(x) :
prod = prod * (x % 10)
x = x // 10
# return the product of digits
return prod
# Function to find the count
def find_count(n) :
# hash map for
# counting frequency
mpp = {}
for i in range(1, n + 1):
# counting freq of each element
x = digit_prod(i)
if x in mpp :
mpp[x] += 1
else :
mpp[x] = 1
ans = 1
maxm = 0
for value in mpp.values() :
# find the maximum
if (value > maxm) :
maxm = value
ans = 1
elif (value == maxm) :
# count the number of groups having
# size of equal to largest group.
ans = ans + 1
return ans
# Driver code
# initialise N
N = 13
print(find_count(N))
# This code is contributed by Sanjit_PrasadC#
// C# implementation to count the
// groups having largest size while
// grouping is according to
// the product of its digits
using System;
using System.Collections;
using System.Collections.Generic;
using System.Text;
class GFG{
// Function to find out product of digit
static int digit_prod(int x)
{
int prod = 1;
// Calculate product
while (x != 0)
{
prod *= x % 10;
x = x / 10;
}
// Return the product of digits
return prod;
}
// Function to find the count
static int find_count(int n)
{
// Hash map for counting frequency
Dictionary mpp = new Dictionary();
for(int i = 1; i <= n; i++)
{
// Counting freq of each element
int t = digit_prod(i);
if (mpp.ContainsKey(t))
{
mpp[t]++;
}
else
{
mpp[i] = 1;
}
}
int ans = 1;
int maxm = 0;
foreach(KeyValuePair x in mpp)
{
// Find the maximum
if (x.Value > maxm)
{
maxm = x.Value;
ans = 1;
}
else if (x.Value == maxm)
{
// Count the number of groups having
// size of equal to largest group.
ans++;
}
}
return ans;
}
// Driver Code
public static void Main(string[] args)
{
// Initialise N
int N = 13;
Console.Write(find_count(N));
}
}
// This code is contributed by rutvik_56 输出：
3