不改變元音和子音的相對位置的單字排列？

假設我們有一個包含 n 個元素的字串 (n

方法很簡單。我們必須計算給定字串中元音和輔音的數量，然後我們必須找到僅可以排列元音的方式有多少種，然後找到僅排列輔音的方式的數量，然後將這兩個結果相乘得到總路數。

演算法

arrangeWayCount(str)

Begin
   define an array ‘freq’ to store frequency.
   count and place frequency of each characters in freq array. such that freq[‘0’] will hold
   frequency of letter ‘a’, freq[1] will hold frequency of ‘b’ and so on.
   v := number of vowels, and c := number of consonants in str
   vArrange := factorial of v
   for each vowel v in [a, e, i, o, u], do
      vArrange := vArrange / factorial of the frequency of v
   done
   cArrange := factorial of c
   for each consonant con, do
      cArrange := cArrange / factorial of the frequency of con
   done
   return vArrange * cArrange
End

範例

#include <iostream>
using namespace std;
long long factorial(int n){
   if(n == 0 || n == 1)
      return 1;
   return n*factorial(n-1);
}
long long arrangeWayCount(string str){
   long long freq[27] = {0}; //fill frequency array to 0
   int v = 0, c = 0;
   for (int i = 0; i < str.length(); i++) {
      freq[str[i] - &#39;a&#39;]++;
      if (str[i] == &#39;a&#39; || str[i] == &#39;e&#39; || str[i] == &#39;i&#39; || str[i] == &#39;o&#39; || str[i] == &#39;u&#39;) {
         v++;
      }else
         c++;
   }
   long long arrangeVowel;
   arrangeVowel = factorial(v);
   arrangeVowel /= factorial(freq[0]); // vowel a
   arrangeVowel /= factorial(freq[4]); // vowel e
   arrangeVowel /= factorial(freq[8]); // vowel i
   arrangeVowel /= factorial(freq[14]); // vowel o
   arrangeVowel /= factorial(freq[20]); // vowel u
   long long arrangeConsonant;
   arrangeConsonant = factorial(c);
   for (int i = 0; i < 26; i++) {
      if (i != 0 && i != 4 && i != 8 && i != 14 && i != 20)
      arrangeConsonant /= factorial(freq[i]); //frequency of all characters except vowels
   }
   long long total = arrangeVowel * arrangeConsonant;
   return total;
}
main() {
   string str = "computer";
   long long ans = arrangeWayCount(str);
   cout << "Possible ways to arrange: " << ans << endl;
}

輸出

Possible ways to arrange: 720

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