Count of substrings consisting of even number of vowels | C ++ program to implement the above approach ; Utility function to check if a character is a vowel ; Function to calculate and return the count of substrings with even number of vowels ; Stores the count of substrings with even and odd number of vowels respectively ; Update count of vowels modulo 2 in sum to obtain even or odd ; Increment even / odd count ; Count substrings with even number of vowels using Handshaking Lemma ; Driver Code
#include <bits/stdc++.h> NEW_LINE using namespace std ; bool isVowel ( char c ) { if ( c == ' a ' c == ' e ' c == ' i ' c == ' o ' c == ' u ' ) return true ; return false ; } void countSubstrings ( string s , int n ) { int temp [ ] = { 1 , 0 } ; int result = 0 , sum = 0 ; for ( int i = 0 ; i <= n - 1 ; i ++ ) { sum += ( isVowel ( s [ i ] ) ? 1 : 0 ) ; sum %= 2 ; temp [ sum ] ++ ; } result += ( ( temp [ 0 ] * ( temp [ 0 ] - 1 ) ) / 2 ) ; result += ( ( temp [ 1 ] * ( temp [ 1 ] - 1 ) ) / 2 ) ; cout << result ; } int main ( ) { int n = 5 ; string s = " abcde " ; countSubstrings ( s , n ) ; }