Ositus

import itertools
def ie(v, w, m, x, y):
    t=0
    S=[]
    P=[]
    for z in range(x):
        for j in range(y):
            S.append(v[m[z][j]][1])
            P.append(v[m[z][j]][0])
        S.pop()
        if v[m[z][-1]][0]<=max(S):
            t+=2**(w-(v[m[z][-1]][1]-min(P))-1)
    return t
s=input()
p=len(s)
k=[]
l=[]
for i in range(p):
    if (s[i] in k):
        l.append([k.index(s[i]), i])
        k[k.index(s[i])]=False
    k.append(s[i])
n=len(l)
u=0
for i in range(n):
    u+=2**(p-(l[i][1]-l[i][0])-1)
for i in range(2, n+1):
    m=list(itertools.combinations(list(range(0, n)), i))
    u+=(-1)**(i-1)*ie(l, p, m, len(m), i)
print((2**(p-1)-u)%(10**9+7))

Test 1

Group: 1, 2, 3

Verdict: ACCEPTED

Test 2

Group: 1, 2, 3

Verdict: ACCEPTED

Test 3

Group: 1, 2, 3

Verdict: WRONG ANSWER

Test 4

Group: 1, 2, 3

Verdict: WRONG ANSWER

Test 5

Group: 2, 3

Verdict: TIME LIMIT EXCEEDED

Test 6

Group: 3

Verdict: TIME LIMIT EXCEEDED

Test 7

Group: 3

Verdict: TIME LIMIT EXCEEDED