Help me in solving DSSA19 problem

help
,
1

My issue

the code is executed but it showing as partially correct

My code

def max_people_in_towers(T, test_cases):
    for i in range(T):
        N = test_cases[i][0]
        S = test_cases[i][1]

        count = 0
        if S[:2] == "00":
            count += 1
            S = "1" + S[1:]

        if S[-2:] == "00":
            count += 1
            S = S[:-1] + "1"

        i = 1
        while i < len(S) - 1:
            if S[i - 1] == "0" and S[i] == "0" and S[i + 1] == "0":
                S = S[:i] + "1" + S[i + 1:]
                count += 1
                i += 2
            else:
                i += 1

        print(count)

# Input
T = int(input())
test_cases = []
for _ in range(T):
    N = int(input())
    S = input().strip()
    test_cases.append((N, S))

# Output
max_people_in_towers(T, test_cases)

Learning course: Kalasalingam Academy of Research and Education
Problem Link: CodeChef: Practical coding for everyone