Buggy python submission (verdict: Time Limit Exceeded):
def resolve():
    N = int(input())
    S = input()
    cnt = 0
    for i in range(0, N-3):
        si = S[i]
        for a in retA(si):
            idx1 = S.find(a, i)
            b = retB(a, si)
            while idx1 != -1:
                cnt += S[idx1+1:].count(b)
                if 2*idx1 - i < N:
                    if S[2*idx1 - i] == b:
                        cnt -= 1
                idx1 = S.find(a, idx1+1)

    print(cnt)

def retA(a):
    if a == 'R':
        A = ('G', 'B')
    elif a == 'G':
        A = ('R', 'B')
    elif a == 'B':
        A = ('R', 'G')
    return A

def retB(a, x):
    if (a == 'R' or x == 'R') and (a == 'G' or x == 'G'):
        b = 'B'
    elif (a == 'B' or x == 'B') and (a == 'G' or x == 'G'):
        b = 'R'
    elif (a == 'B' or x == 'B') and (a == 'R' or x == 'R'):
        b = 'G'
    return b

if __name__ == '__main__':
    resolve()

Fixed submission:
def resolve():
    N = int(input())
    S = input()
    rc = S.count('R')
    bc = S.count('B')
    gc = S.count('G')

    cnt = rc * bc * gc

    for i in range(0, N):
        for d in range(0, N):
            j = i + d
            k = j + d
            if N < k+1:
                break
            if S[i] != S[j] and S[j] != S[k] and S[k] != S[i]:
                cnt -= 1
    print(cnt)

if __name__ == '__main__':
    resolve()

Buggy python submission (verdict: Time Limit Exceeded):
def resolve():
    N = int(input())
    S = input()
    cnt = 0
    for i in range(0, N-3):
        si = S[i]
        for a in retA(si):
            idx1 = S.find(a, i)
            while idx1 != -1:
                b = retB(a, si)
                cnt += S[idx1+1:].count(b)
                if 2*idx1 - i < N:
                    if S[2*idx1 - i] == b:
                        cnt -= 1
                idx1 = S.find(a, idx1+1)

    print(cnt)

def retA(a):
    if a == 'R':
        A = ('G', 'B')
    elif a == 'G':
        A = ('R', 'B')
    elif a == 'B':
        A = ('R', 'G')
    return A

def retB(a, x):
    if (a == 'R' or x == 'R') and (a == 'G' or x == 'G'):
        b = 'B'
    elif (a == 'B' or x == 'B') and (a == 'G' or x == 'G'):
        b = 'R'
    elif (a == 'B' or x == 'B') and (a == 'R' or x == 'R'):
        b = 'G'
    return b

if __name__ == '__main__':
    resolve()

Fixed submission:
def resolve():
    N = int(input())
    S = input()
    rc = S.count('R')
    bc = S.count('B')
    gc = S.count('G')

    cnt = rc * bc * gc

    for i in range(0, N):
        for d in range(0, N):
            j = i + d
            k = j + d
            if N < k+1:
                break
            if S[i] != S[j] and S[j] != S[k] and S[k] != S[i]:
                cnt -= 1
    print(cnt)

if __name__ == '__main__':
    resolve()

Buggy python submission (verdict: Time Limit Exceeded):
def resolve():
    N = int(input())
    S = input()
    cnt = 0
    for i in range(0, N-3):
        si = S[i]
        for a in retA(si):
            idx1 = S.find(a, i)
            while idx1 != -1:
                b = retB(a, si)
                cnt += S[idx1+1:].count(b)
                if 2*idx1 - i < N:
                    if S[2*idx1 - i] == b:
                        cnt -= 1
                idx1 = S.find(a, idx1+1)

    print(cnt)

def retA(a):
    if a == 'R':
        A = ('G', 'B')
    elif a == 'G':
        A = ('R', 'B')
    elif a == 'B':
        A = ('R', 'G')
    return A

def retB(a, x):
    if (a == 'R' or x == 'R') and (a == 'G' or x == 'G'):
        b = 'B'
    elif (a == 'B' or x == 'B') and (a == 'G' or x == 'G'):
        b = 'R'
    elif (a == 'B' or x == 'B') and (a == 'R' or x == 'R'):
        b = 'G'
    return b

if __name__ == '__main__':
    resolve()


Fixed submission:
def resolve():
    N = int(input())
    S = input()
    rc = S.count('R')
    bc = S.count('B')
    gc = S.count('G')

    cnt = rc * bc * gc

    for i in range(0, N):
        for d in range(0, N):
            j = i + d
            k = j + d
            if N < k+1:
                break
            if S[i] != S[j] and S[j] != S[k] and S[k] != S[i]:
                cnt -= 1
    print(cnt)

if __name__ == '__main__':
    resolve()