47's Strings

Diana sent a message "S" to agent 47 in an encrypted language so that no one else can decode it.

Now a string in the encrypted language is said to be valid if and only if it contains the characters '$' or '&' . Agent 47 decided to count the number of valid sub-strings of the message "S" sent by Diana.

P.S. - '$' and '&' characters are considered as 4 -> '$' and 7 -> '&' in a key-board.

Can you help Agent 47, in counting the total no. of valid substrings and the encrypted message.

Note: Two sub-strings are different if they occur at different positions in the message.

Example:

Input:  s = "$bcd"
Output: 4

Approach

C++

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

void fourtySevenString(string s)
{
    long long ans = 0, k = 0, count = 0;
    for (int i = 0; i < s.length(); i++)
    {
        if (s[i] == '$' || s[i] == '&')
        {
            ans += (s.length() - i) * (count);
            ans += (s.length() - i);
            count = 0;
        }
        else
        {
            count++;
        }
    }
    cout << ans << "\n";
}
int main()
{

    string s = "$bcd";

    fourtySevenString(s);

    return 0;
}