包含恰好X个元音字母的长度为K的子串的数量

#include <bits/stdc++.h>
using namespace std;

// function to count the total number of vowels in a string
int cntVowels(string alpha) {
   int vows = 0;
   for (int i = 0; i < alpha.length(); i++) {
      if (alpha[i] == 'a' || alpha[i] == 'e' || alpha[i] == 'i' || alpha[i] == 'o' ||
          alpha[i] == 'u' || alpha[i] == 'A' || alpha[i] == 'E' || alpha[i] == 'I' ||
          alpha[i] == 'O' || alpha[i] == 'U')
          vows++;
   }
   return vows;
}
int cntSubstr(string str, int K, int X) {
   int cnt = 0;
   // traverse the string and check for the total number of vowels in each substring of length K
    for (int i = 0; i <= str.length() - K; i++) {
       // get the substring of length K starting from index i
       string sub = str.substr(i, K);
       // check if the total number of vowels in the substring is equal to X, then increment cnt
       if (cntVowels(sub) == X)
          cnt++;
   }
   return cnt;
}
// Driver code
int main(void) {
   string str = "TutorialsPoint";
   int K = 3, X = 2;
   cout << "The total number of substrings of length " << K << " containing " << X << " vowels is " << cntSubstr(str, K, X);
   return 0;
}

The total number of substrings of length 3 containing 2 vowels is 6

#include <bits/stdc++.h>
using namespace std;
bool isVowel(char ch) {
   // convert character to lowercase
   ch = tolower(ch);
   return (ch == 'a' || ch == 'e' || ch == 'i' || ch == 'o' || ch == 'u');
}
int cntSubstr(string str, int K, int X) {
   // To store total vowels
   int total_vow = 0;
   // Count the number of vowels in the first window
   for (int p = 0; p < K; p++)
       if (isVowel(str[p]))
            total_vow++;
   // to store the total number of substrings of length K containing X vowels
   int cnt = 0;
   // If the first window contains exactly X vowels, initialize cnt as 1
   cnt = total_vow == X ? 1 : 0;
   // traverse the string
   for (int i = 1; i <= str.length() - K; i++) {
      // exclude the (i - 1)th character from the window and update the total_vow
      total_vow = isVowel(str[i - 1]) ? total_vow - 1 : total_vow;
      // Add [i-1+K]th character to the current window and update total_vow
      total_vow = isVowel(str[i - 1 + K]) ? total_vow + 1 : total_vow;
      // If the current window contains exactly X vowels, increment cnt
      if (total_vow == X)
          cnt++;
   }
   return cnt;
}
int main(void) {
   string str = "TutorialsPoint";
   int K = 3, X = 2;
   cout << "The total number of substrings of length " << K << " containing " << X << " vowels is " << cntSubstr(str, K, X);
   return 0;
}

The total number of substrings of length 3 containing 2 vowels is 6