Buggy python submission (verdict: Time Limit Exceeded):
def main():
    s = input()
    d = {0: 0}
    for i in s:
        d2 = dict()

        for j in d.keys():
            k = d[j]
            if i != "1":
                temp = max(j-1, 0)
                if temp not in d2:
                    d2[temp] = [k-1]
                else:
                    d2[temp].append(k-1)
            if i != "0":
                if j+1 not in d2:
                    d2[j+1] = [min(0, k+1)]
                else:
                    d2[temp].append(min(0, k+1))

        d = dict()
        for j in d2.keys():
            d[j] = max(d2[j])

        for i in d2.keys():
            if i-1 in d:
                if d[i] == d[i-1]:
                    d.pop(i)
                    continue
            if i-2 in d:
                if d[i] == d[i-2]:
                    d.pop(i)

    ans2 = 10**10
    for i, j in d.items():
        ans2 = min(ans2, i-j)
    print(ans2)


main()


Fixed submission:
def main():
    S = input()
    size = [[[[0, 0]], []], [[], []]]
    length = 0

    for s in S:
        size2 = [[[], []], [[], []], [[], []]]
        if s != "0":
            for i in range(2):
                for j in range(2):
                    if size[i][j]:
                        for x, y in size[i][j]:
                            if y == length+i:
                                size2[i+1][j ^ 1].append([y+1, y+1])
                                if x != y:
                                    size2[i][j ^ 1].append([x+1, y-1])
                            else:
                                size2[i][j ^ 1].append([x+1, y+1])
        if s != "1":
            for i in range(2):
                for j in range(2):
                    if size[i][j]:
                        for x, y in size[i][j]:
                            if x == 0:
                                size2[i+1][j].append([0, 0])
                                if x != y:
                                    size2[i][j ^ 1].append([x+1, y-1])
                            else:
                                size2[i][j ^ 1].append([x-1, y-1])
        if len(size2[0][0]+size2[0][1]) == 0:
            size2 = size2[1:]
            length += 1
        else:
            size2.pop()
        for i in range(2):
            for j in range(2):
                size2[i][j] = sorted(size2[i][j])
        size = [[[], []], [[], []]]
        for i in range(2):
            for j in range(2):
                if len(size2[i][j]) == 0:
                    continue
                elif len(size2[i][j]) == 1:
                    size[i][j] = size2[i][j]
                    continue
                size[i][j] = [size2[i][j][0]]
                for x, y in size2[i][j][1:]:
                    p, q = size[i][j][-1]
                    if y <= q:
                        continue
                    if x <= q+2:
                        size[i][j][-1][1] = y
                    else:
                        size[i][j].append([x, y])
    print(length)


main()

Buggy python submission (verdict: Time Limit Exceeded):
def main():
    s = input()
    m = 1
    t = [None]*m
    t[0] = 0
    for i in s:
        t2 = [[] for _ in [0]*m]
        for j in range(m):
            k = t[j]
            if k is None:
                continue
            if i != "1":
                t2[max(j-1, 0)].append(k-1)
            if i != "0":
                if j+1 < m:
                    t2[j+1].append(min(0, k+1))
                else:
                    t2.append([min(0, k+1)])
                    t.append(None)
                    m += 1
        for j in range(m):
            if t2[j]:
                t[j] = max(t2[j])
            else:
                t[j] = None
        for i in range(m-1, 1, -1):
            if t[i] == t[i-1]:
                t[i] = None
            if t[i] == t[i-2]:
                t[i] = None
        for i in range(m-1, -1, -1):
            if t[i] is None:
                t.pop()
                m -= 1
            else:
                break

    ans = 10**10
    for i in range(m):
        if t[i] is not None:
            ans = min(ans, i-t[i])
    print(ans)


main()

Fixed submission:
def main():
    S = input()
    size = [[[[0, 0]], []], [[], []]]
    length = 0

    for s in S:
        size2 = [[[], []], [[], []], [[], []]]
        if s != "0":
            for i in range(2):
                for j in range(2):
                    if size[i][j]:
                        for x, y in size[i][j]:
                            if y == length+i:
                                size2[i+1][j ^ 1].append([y+1, y+1])
                                if x != y:
                                    size2[i][j ^ 1].append([x+1, y-1])
                            else:
                                size2[i][j ^ 1].append([x+1, y+1])
        if s != "1":
            for i in range(2):
                for j in range(2):
                    if size[i][j]:
                        for x, y in size[i][j]:
                            if x == 0:
                                size2[i+1][j].append([0, 0])
                                if x != y:
                                    size2[i][j ^ 1].append([x+1, y-1])
                            else:
                                size2[i][j ^ 1].append([x-1, y-1])
        if len(size2[0][0]+size2[0][1]) == 0:
            size2 = size2[1:]
            length += 1
        else:
            size2.pop()
        for i in range(2):
            for j in range(2):
                size2[i][j] = sorted(size2[i][j])
        size = [[[], []], [[], []]]
        for i in range(2):
            for j in range(2):
                if len(size2[i][j]) == 0:
                    continue
                elif len(size2[i][j]) == 1:
                    size[i][j] = size2[i][j]
                    continue
                size[i][j] = [size2[i][j][0]]
                for x, y in size2[i][j][1:]:
                    p, q = size[i][j][-1]
                    if y <= q:
                        continue
                    if x <= q+2:
                        size[i][j][-1][1] = y
                    else:
                        size[i][j].append([x, y])
    print(length)


main()