https://leetcode-cn.com/problems/vowels-of-all-substrings/
思维题 若i是元音字母,则看一下组合数即可
class Solution {
public:
long long countVowels(string w) {
long long ans=0;
long long n=w.size();
for(long long i=0;i<n;i++)
{
if(w[i]=='a' || w[i]=='e' || w[i]=='i' || w[i]=='o' || w[i]=='u')
ans=ans+(i+1)*(n-i);
}
return ans;
}
};