题解 | 小红的双生数

def solved():
    s = input()
    if len(s) % 2 == 1:
        k = (len(s)+1) // 2
        print("1100" * (k//2) + "11" * (k%2))
    else:
        for i in range(0, len(s), 2):
            if s[i] == s[i+1] and i > 0 and s[i] == s[i-1]:
                c, j = (int(s[i]) + 1) // 10, i-2
                while j >= 0 and c == 1:
                    c = (int(s[j]) + 1) // 10
                    if c == 0 and j > 0 and int(s[j]) + 1 == int(s[j-1]):
                        c = (int(s[j]) + 2) // 10
                    j -= 2
                if c == 1:
                    k = len(s) // 2 + 1
                    print("1100" * (k//2) + "11" * (k%2))
                else:
                    k = (len(s) - j - 4) // 2
                    if int(s[j]) == int(s[j+2])+1:
                        print(s[:j+2]+chr(ord(s[j+2])+2)*2+"0011" * (k//2) + "00" * (k%2))
                    else:
                        #print(len(s[:j+2]+chr(ord(s[j+2])+1)*2+"0011" * (k//2) + "00" * (k%2)))
                        print(s[:j+2]+chr(ord(s[j+2])+1)*2+"0011" * (k//2) + "00" * (k%2))
                return 
            if s[i] != s[i+1]:
                s_ = chr(max(ord(s[i]), ord(s[i+1])))
                if i > 0 and s_ == s[i-1]:          
                    c, j = (int(s[i]) + 1) // 10, i-2
                    while j >= 0 and c == 1:
                        c = (int(s[j]) + 1) // 10
                        if c == 0 and j > 0 and int(s[j]) + 1 == int(s[j-1]):
                            c = (int(s[j]) + 2) // 10
                        j -= 2
                    if c == 1:
                        k = len(s) // 2 + 1
                        print("1100" * (k//2) + "11" * (k%2))
                    else:
                        k = (len(s) - j - 4) // 2
                        if int(s[j]) == int(s[j+2])+1:
                            print(s[:j+2]+chr(ord(s[j+2])+2)*2+"0011" * (k//2) + "00" * (k%2))
                        else:
                            print(s[:j+2]+chr(ord(s[j+2])+1)*2+"0011" * (k//2) + "00" * (k%2))
                else:
                    k = (len(s)-i-2) // 2
                    print(s[:i]+s_*2+"0011" * (k//2)+"00"*(k%2))
                return

if __name__ == "__main__":
    solved()