Ositus

#include <iostream>
#include <math.h>
#include <vector>
#include <algorithm>
using namespace std;

const int charCount = 26;
int toInt(char c) {
    return (int) c - 97;
}

unsigned long long all(unsigned long long len) {
    if (len < 0) len = 0;
    unsigned long long res = 1;
    for (unsigned long long i = 0; i < len; i++) {
        res *= 2;
    }
    return res;
}

unsigned long long solve(string value) {
    unsigned long long res = 1;
    unsigned long long history[value.length()];

    int chars [charCount];
    fill_n(chars, charCount, -1);

    for (unsigned long long i = 0; i < value.length(); i++) {

        int c = toInt(value[i]);
        if (chars[c] != -1) {
            unsigned long long start = history[chars[c]];
            unsigned long long end = all(i - chars[c]) - 1;
            cout <<"|  "<< value[i]  <<" res: "<< res <<" i: "<< i <<", last: "<< chars[c] <<", start: "<< start <<", end: "<< end <<endl;
            res += start * end;
        } else if (i != 0) {
            res *= 2;
        }
        cout << value.substr(0, i + 1) <<" = "<< res << endl;

        history[i] = res;
        chars[c] = i;
    }

    return res;
}

int main() {
    string str;
    cin >> str;
    cout << solve(str) % (1000000000 + 7);
}

Test 1

Group: 1, 2, 3

Verdict: WRONG ANSWER

Test 2

Group: 1, 2, 3

Verdict: WRONG ANSWER

Test 3

Group: 1, 2, 3

Verdict: WRONG ANSWER

Test 4

Group: 1, 2, 3

Verdict: WRONG ANSWER

Test 5

Group: 2, 3

Verdict: WRONG ANSWER

Test 6

Group: 3

Verdict: WRONG ANSWER

Test 7

Group: 3

Verdict: OUTPUT LIMIT EXCEEDED